Crypto glossary

Develop your crypto skills step by step to become little by little expert on this new ecosystem.

For starters

All-in :

It means putting all your capital at stake on the same cryptocurrency at the same time. Might as well tell you it's usually a bad strategy.

Altcoin :

All cryptocurrencies except Bitcoin (Ethereum, Ripple, Dash, Monero…) are collectively referred to as Altcoins. There are about 5000 of them.

Bear Market :

Market showing a downward trend.

Bitcoin :

Bitcoin is the first cryptocurrency, created by Satoshi Nakamoto. Beyond being the most well-known and most highly capitalized cryptocurrency, it is also totally decentralized, i.e. no authority controls it.

Bitcoin Cash :

It's a cryptocurrency derived from Bitcoin following a hard fork that took place in August 2017. Learn more about Bitcoin Cash : What is Bitcoin Cash (BCH) ?

Blockchain :

The Blockchain is a data register used as an account book for cryptocurrencies. It differs from a traditional database by the fact that it is replicated and immutable and is intended to record transactions, which can be of multiple natures. For more information and details : What is the Blockchain ?

Blockchain Explorer :

A website through which information from transactions included in blocks can be viewed in humanly intelligible terms. This is useful information for consulting the status of a transaction in progress, for checking the receipt of payments, and for consulting the code of the various smart-contracts.

Blocks :

Transactions in a blockchain are recorded in the form of blocks, whose hashs ensure security and immutability. Each block is cryptographically linked to the previous one, hence the name blockchain.

Bubble :

As in traditional finance, a bubble is equivalent to an artificial rise in prices, caused by speculation, which ends in a burst and therefore a sharp fall.

Bull Market :

Market showing an upward trend.

Cold storage :

Cold storage means keeping a reserve of Bitcoin offline, which is allowed when there are Bitcoin private keys created and stored in a secure, offline environment. Storing funds on platforms or on a connected computer presents significant risks incompatible with large amounts of money.

Confirmations :

After a transaction has been included in block n, it has a confirmation. As soon as a new n+1 block is released and distributed in the network, the transaction has two confirmations. Each additional block linked to the Blockchain adds one confirmation to the transaction. It is considered that 6 or more confirmations are sufficient to ensure the non-reversibility of the transaction. It should be noted that 6 confirmations are acceptable for the bitcoin blockchain. For the other blockchains, it's different.

Cryptocurrency :

It is a digital currency, the security of which relies on cryptography.

Décentralization :

A number of cryptocurrency are based on decentralization. In a decentralized cryptocurrency, any change in its operation must be subject to a broad consensus throughout the community. This principle is opposed to state currencies where a central bank makes the decisions, and to private payment systems such as Paypal, where a company controls the system.

Ethereum :

Ethereum is a cryptocurrency, created in 2014 by Vitalik Buterin. It is the second most capitalized cryptography after Bitcoin, which has the particularity of being able to execute smart contracts. More information about the other features and possibilities that the Ethereum allows you to read about on : What is Ethereum ETH ?

Fees :

Transaction fees are a feature of the Bitcoin protocol. They are paid by the issuer of a transaction, and are collected by the miner who enables the release of the block containing the transaction. They provide an economic incentive to mine on the Bitcoin network. They are calculated according to the difference between the input and the output of a transaction.

FIAT Money :

State currency distributed by a central bank, such as the euro or the dollar. The name FIAT is derivated from the term fiduciary which comes from the Latin "fiducia", trust. The value of a FIAT money is therefore based on the trust placed in it, and not on an underlying such as currencies based on the gold standard.

Fork :

A Fork is a split of the blockchain, which results in two incompatible networks. This split can disappear after a few minutes or hours, and is then called soft fork, and it is a relatively frequent phenomenon. Otherwise, it is called a hard fork. The two blockchains are then definitively separated, and a new cryptocurrency is created. The Bitcoin Cash is a perfect example of a hard fork having taken place.

Hard Fork :

A hard fork is a permanent divergence on a blockchain. The blocks of the 2 parallel chains are no longer compatible due to major changes in the consensus rules.

Hardware wallet

This is a type of wallet that allows the user to store his or her private keys on specialized secure equipment.

Hodl :

Following a typing error by a user on a forum that has become a meme, the word hodl means "hold". Hodlers refuse to sell their cryptos regardless of the state of the market.

Marketcap :

The market cap represents the total value of a currency, calculated by multiplying the number of units in circulation by the value of the unit.

Miner :

If we take the Ethereum blockchain as an example, the miner is a computer hardware whose role is to validate the blocks on the network, on which an Ethereum node has been installed. The role of this node is to find the proof of valid work for the new blocks, by repeated and incremental hashing of a nonce.

Peer-to-peer :

This term characterizes a computer network whose users are both servers and clients, i.e. they share the same resources without the need for a centralized server system.

Public Key:

The public key is derived directly from a private key via an ECDSA algorithm considered irreversible (the calculation power and the time required would be considerable). It allows to generate all the public addresses linked to the private key, by derivation in Base58Check.

Pumping :

Action which consists in inciting to invest in a cryptocurrency in order to artificially raise prices, and thus be able to sell at the high price.

Return On Investment (ROI) :

The ROI is a percentage that is calculated by dividing the profit made by the investments made. For example, if you have doubled your initial investment, this equals a ROI of 100%.

Reward :

The reward refers to the amount collected by the miner when he validates a block. This is a controlled (or uncontrolled) cryptoactive emission intended for the miner having provided the correct nonce, to which is added the sum of the fees of the transactions included in the block. On Ethereum, the emission is currently 3 ethers per block of transactions and will increase to 2 ethers per block with Constantinople.

Satoshi :

As a tribute to its creator, Satoshi Nakamoto, it was decided that the smallest subdivision of Bitcoin would be called a Satoshi. Thus, 1 Satoshi = 0.00000001 BTC.

Satoshi Nakamoto :

Satoshi Nakamoto is the pseudonym used by the creator(s) of Bitcoin. His identity remains unknown to this day.

Scam :

It is an illegal plan for making money, especially one that involves tricking people. They are unfortunately common in the cryptocurrencies ecosystem.

Seed :

The seed is a security that allows a user to easily retrieve his wallet. It is a list of words provided in a specific order that contain all the information needed to restore the private key. If a malicious individual falls on this seed, he will be able to send the funds to a wallet he controls, so it is strongly advised to keep it very carefully (and offline).

Transaction :

A transaction, also known as an On-chain transaction, represents an exchange of value, data or property between two users. Transactions are unencrypted and are viewable via Blockchain explorers (Blockchain explorer). Following its diffusion on the network, this transaction awaiting validation is found in the Memory Pool. It is recorded in the Blockchain register once it has been included in a block and then validated.

Wallet :

A wallet, in the crypto world, is a software or device that allows to store private keys and to use them to send transactions on a blockchain. For Ethereum transactions, we recommend the Nano S/X/blue Ledger as a physical wallet, Metamask as a client web3, and Cypher Browser as a mobile wallet. More info: What is the best Bitcoin Wal let?

White Paper :

The White Paper is a document presenting all the information related to a particular cryptocurrency or to a particular Blockchain. In general, this document makes it possible to convince - or not - potential investors of the interest of the project in question.

To go further

Block Height :

The first block, the genesis block, is block number 0. From there, each block is numbered according to its order of arrival. The block #7080000 is thus the 7080001th block of the Blockchain.

Calculation Power :

Computing power is the number of hash per second calculated by a machine or even by the entire network. On Ethereum the computing power is of the order of 180 TerraHash/sec. The machines spend electricity in order to perform these operations.

Consensus :

Consensus is achieved when different nodes (often the majority of nodes on the network) have the same blocks in their local Blockchain. In case of a difference between the local Blockchains of the nodes, we speak of fork. Reorganization of the network is done by selecting the longest chain from the fork. Not to be confused with the consensus rules..

Consensus Rules :

Consensus rules allow full nodes (whole nodes) to remain in consensus with other nodes in the network. It is a specific set of rules that all nodes will systematically apply when considering the validity of a block and its transactions. They concern only the validity of blocks and transactions. For example, the Ethereum consensus rules require that blocks only create a certain number of ethers. If a block creates more ethers than allowed, all full nodes will reject this block, even if all other nodes and miners in the world accept it. Adding new consensus rules can usually be done by soft fork, while removing any consensus rules requires a hard fork.

Dapp - Decentralized Apps

The Blockchain Ethereum allows to implement and run computer code in such a decentralized way that it can be implemented and run on all nodes of the network at the same time, i.e. on all nodes of the network at the same time. This makes this code "immortal", public, and usable by everyone. This code is also called "smart-contract". Smart-contracts give rise to decentralized applications, accessible via a classic web browser and which therefore benefit from the same characteristics.

Difficulty :

Difficulty is a parameter allowing to ensure a regular average time between 2 blocks according to the calculation power available on the network. On Ethereum, its value is recalculated all the blocks by readjusting itself in relation to the moving average over the last 2048 blocks. This ensures an average time of 15.7 seconds between 2 block validations, whatever the power changes on the network. The higher the difficulty, the smaller the common target for the miners is.

ERC-20 :

The Ethereum Request for Comment #20 (ERC20) is the most widespread standard for creating tokens. The ERC20 are fungible tokens that can have utility, monetary, or governance value within a Dapp. An ERC-20 token may also be of no use at all apart from its own existence.

ERC-721 :

ERC-721 is the first standard allowing the creation of non-fungible tokens. This allows, contrary to ERC-20 tokens, the creation of tokens with a unique identity. They are notably used in the Cryptokitties project where each digital cat has its own identity in the form of an ERC-721 token on the Ethereum blockchain and in the Decentraland project where each ERC-721 token gives a property right to a piece of digital land. Some projects wish to use the ERC-721 as digital and exchangeable representations of traditional assets.

Ethereum Block :

On Ethereum, the blocks are mined on average every 15.7 seconds and have a capacity of 8,000,000 units of gas.

Ethereum Foundation

The purpose of the Ethereum Foundation is to promote and help finance research and development projects for technologies that can improve the Ethereum Protocol. According to information provided by Vitalik Buterin, the Ethereum Foundation has had at most 3M ETH, and would have today a little more than 500k ETH at its disposal, the rest having been used to finance projects.

Hash function :

Irreversible protection algorithm for establishing a unique digital fingerprint of a string of characters of variable length (can be a document, an audio file, a public key, etc). Two perfectly identical documents have the same hash as a result of applying the same hash function. However, if they differ, even minimally, the hashes of the two documents will be noticeably different. This makes it possible to determine the integrity of considerable amounts of data without having to look at them.

Gas - Usage fees:

On Ethereum, the blocks have a maximum capacity of 8,000,000 gas units. Each operation has a cost established in gas units. For example, a classic transaction from one account to another costs 21,000 gas units. Transactions using complex functionality in the smart-contracts can cost much more in gas units. Each gas unit has a price denominated in Gwei (1 Gwei = 0.000000001 ETH) defined by market demand. To know the price of the gas unit at any time, we recommend the Chrome Ethereum Gas Price extension.

Genesis Block :

This is block n°0 of a Blockchain, the first block sent which allows to initialize the network. It is the only block that does not refer to the previous block. On Ethereum the genesis block was mined on July 30, 2015 at 15h36 UTC.

Gwei :

Gwei is a unit of account that refers to 0.000000001 ether. It is also equivalent to 1000 wei, the smallest unit of account in Ethereum. It is used to calculate the price of a unit of gas.

Halving :

In a crypto currency such as the Bitcoin, each time a new block is validated, a production of a certain number of bitcoins results. The translation of the English word "Halving" means halving. The protocol states that approximately every 4 years a "halving" takes place on the Bitcoin Blockchain. The number of bitcoins generated during the validation of a new block is then halved. The consequence is that this asset becomes scarce, which is one of the main characteristics that gives it value. This mechanism determines the final limit of 21 million Bitcoins that can be reached. So far, the Bitcoin network has witnessed 3 "Halvings": the first one in November 2012, the second one in July 2016 and the third and last one in May 2020.

Hash :

A single numeric fingerprint from a hash function that transforms an input of any number of characters or data into a single fixed-size character output (see Hash Function).

Hashrate :

Equivalent to the calculation power of a miner or mining network.

ICO (Initial Coin Offering) :

An ICO is a fund raising related to crypto currency, organized most of the time in a decentralized way. More info to read on : What is an ICO ?

Input :

Entries of a transaction represent debits to the Bitcoin issuer account. These are the amounts issued to the receiver. Once the transaction has been validated, the input changes to an output (see Transaction).


Short for Know Your Customer, this term refers to internal processes that identify and verify the identity of a company's customers. Companies of all sizes use these processes to ensure the integrity, probity and compliance of their customers with anti-corruption, money laundering, tax fraud and terrorist financing laws.

Lightning Network :

The Lightning Network is an overlay of the Bitcoin network, designed to overcome the problems of scalability. With the Lightning Network, it should be possible to reach millions of transactions per second on the network. More details on : What is the Lightning Network?

Memory pool :

The memory pool is composed of transactions awaiting validation that have not yet been included in a block and entered in the Blockchain.

Metamask :

Metamask is a wallet web3 that takes the form of a Chrome extension. It recognizes web sites decentralized applications and takes care of packaging all the actions you can perform there in Ethereum transactions for you, greatly facilitating the interaction with the Ethereum Blockchain.

Node :

A node has a full copy of the Blockchain, thus contributing to its security. A node replicates information from other nodes in a synchronization process.

Network :

The Ethereum network is a network open-source peer-to-peer which propagates transactions and blocks to each node of the network. It works thanks to the internet and the consensus rules enacted by the code.

Open-source :

Initiative present in the world of software development consisting in producing software whose licenses respect the charter established by the Open Source Initiative, including the possibilities of free redistribution, creation of derivative works and access to the source code.

Panic Buy :

Acting in panic when there are large market fluctuations, in this case buying assets when the market starts to rise sharply for fear of missing a great opportunity.

Panic Sell :

Acting in panic when there are large market fluctuations, in this case selling your assets when the market starts to fall sharply for fear of losing more money.

Paper wallet :

It is basically a private key generated offline and written on paper. It is possible to send and store funds on the public addresses linked to this private key, but it will be necessary to import the private key on a software connected to the network Ethereum in order to be able to perform an outgoing transaction.

Payment channel :

A payment channel is established by two users via a transaction Ethereum. They decide the amount allocated to the channel and can then make as many transactions as they wish off-chain. A new transaction will be required to close the channel and allocate funds on-chain.

Private key :

If we continue the analogy with messaging, the private key allows access to the full functionality of the address Ethereum, just as the password allows access to the mailbox to view and send messages. The private key is randomly generated by a computer program at the first initialization of a portfolio, and is then derived to produce the Public Key and the different Ethereum addresses. It is in the form of an alpha-numeric character string. Just like messaging clients that allow password recovery in case of loss, the Ethereum network offers security as a mean of recovering the private key, such as generating a SEED at initialization. If its security was not in place when the private key was lost, then the funds will be considered lost as inaccessible.

Proof-of-Stake :

This is one of the methods to achieve a distributed consensus on the blockchain of a crypto-active network. This method requires the validators of blocks to sequester a certain amount of funds in order to be able to validate the blocks of transactions and retrieve the related rewards. The Proof-of-Stake will be implemented progressively on the Ethereum network, first via the Beacon Chain. More information on : What is the Proof of Stake ?

Proof-of-Work :

The Proof-of-Work symbolizes a measure of the resources and time required to complete a task. In the context of crypto-currency, a Proof-of-Work is required when adding new blocks to the Blockchain. The proof-of-work is asymmetric, which means that it must be difficult to provide for the applicant (in this case the miner) but very simple to verify for third parties (the full nodes). On Ethereum, proof of work is provided by the presentation of a valid nonce. This iterative work consists in incrementing the nonce by adding 1 to each trial, until finding a value allowing the hash of the block to be lower than the current target. There is also a mixhash which can also be incremented if all the possibilities of the nonce have been tried without success. In addition to this, the timestamp naturally changes every second, which has a direct consequence on the hash. The nodes will only have to check by generating the hash of the block broadcast (including the nonce and mixhash) on the network to validate or invalidate the block, without having to do the work necessary to discover these parameters again.

Scalability :

It is a term referring to the ability of a Blockchain to be able to handle an increasing number of transactions. Scalability is an essential element in the development of a Blockchain.

Signature :

The signature proves that the funds are in the possession of the issuer when the issuer performs a transaction. The signature is derived from the Private Key according to the ECDSA algorithm, which is considered irreversible. It is therefore possible to pass a fraction of ethers via a transaction signed by the issuer. This signed transaction can then be written in the Blockchain.

Smart-contract :

A smart-contract is a computer program implemented on the Blockchain Ethereum via a transaction. The smart-contracts are then available to anyone who wishes to use them and can no longer be removed, deactivated or censored. The most popular programming languages are Solidity and more recently Vyper. These languages compile into Bytecode so that nodes in the Ethereum network can execute smart-contracts via the EVM.

Staking :

Staking refers to the fact of immobilizing a certain quantity of cryptocurrency in a service allowing to perform a validation such as the proof-of-stake, and to receive the rewards provided for by the service in question.

STO - Security Token Offering :

An STO is a fundraiser for a financial product tokenized. For example, it may be shares in a tokenized company. STOs must be regulated and new token standards such as the ERC-1400 are being developed to facilitate their implementation. There are also projects such as Polymath that seek to create the necessary infrastructure for their deployment and use.

Token :

A token is an asset, generated on blockchain, without being the native asset. For example, MKR is a token of the blockchain Ethereum


Vitalik Buterin :

At the age of 25, Vitalik Buterin is the co-founder of Bitcoin Magazine and the creator of Ethereum.

Volatility :

A volatile market is one in which the market is expected to fluctuate strongly and regularly.

Whales :

Whales refer to people possessing huge amounts of one or more crypto currency. These whales have the ability, due to their colossal capital, to strongly influence the course of the crypto currency in question.

To become an expert

Address :

In the same way as with your email addresses, it is possible to transmit one of your addresses Ethereum in order to receive ethers. An Ethereum address looks like a string of alphanumeric characters. Knowing the address [email protected] does not allow you to access the mailbox, nor to send e-mails from it, just as it is not possible to access funds or to carry out outgoing transactions simply thanks to the Ethereum address. In order to be able to access the mailbox [email protected], you need the password linked to this address, which can be assimilated to the private key linked to the Ethereum address (see Private key). In Ethereum there are user account addresses as well as addresses of smart-contracts. Both use the same format, in hexadecimal, and look like 0x9f8F72aA9304c8B593d555F12eF6589cC3A579A2. Ethereum addresses always start with 0x.


Asymmetric cryptography :

Asymmetric cryptography is an area of cryptography where there is a distinction between public and private data, as opposed to symmetric cryptography where functionality is achieved by the possession of a common secret data between the different participants.

Beacon Chain (Eth 2.0) :

The Beacon Chain, planned for the end of 2019, is a separate Blockchain that communicates with the Blockchain Ethereum. In particular, it will be in charge of managing the Proof-of-Stake and sharding component of the Ethereum network. Thus, the current Main Blockchain (Eth 1.0) will continue to operate via the Proof-of-Work in order to continue to ensure a high level of security during this transition period. Once the beacon chain is implemented, ether holders will be able to migrate their ethers from the current Blockchain to the new Blockchain.

Bytecode :

The smart-contracts Ethereum are listed in the Blockchain Ethereum in their compiled form called the bytecode. The bytecode is an efficient but incomprehensible language for humans, that is why developers do not code directly in bytecode but rather in solidity or vyper, which are more accessible languages that compile in bytecode. It is then executed in EVM (Ethereum Virtual Machine).

Byzantium :

Byzantium is the first phase of deployment of Metropolis, the third phase of network development Ethereum. This update of the Ethereum protocol implemented via a hard-fork to block 4 370 000 in October 2017. Nine EIPs were then implemented with the aim of scalability, confidentiality and security of the Ethereum network.

Casper :

Casper is the name of the protocol Proof-of-Stake intended for Ethereum. It is the confluence of two separate projects called Casper the Friendly Finality Gadget (Casper FFG) and Casper the Friendly GHOST: correct-by-construction (CBC). Casper FFG is a hybrid mechanism that combines consensus and Proof-of-Work with classical PoW via Ethash, a "finality" applied every 50 blocks via PoS validators. CBC casper is a research project that brings together different consensus protocols, where different protocols reach consensus on different types of data. CBC is also a research project around the sharding.

PGP Keys :

PGP keys (for "Pretty Good Privacy") are cryptographic tools to validate the authenticity of a message or to encrypt/decrypt messages.

Coinbase transaction:

The Coinbase transaction is the transaction that remunerates the miners for their work. The new ether units that are added to each block and represent the inflation of the system all come from a coinbase.

ConsenSys :

ConsenSys is one of the leading players in the crypto universe. Founded in October 2014 by Joseph Lubin, the New York-based company promotes and develops solutions aimed at the democratization of "web 3.0", particularly by developing the Ethereum ecosystem. ConsenSys brings together more than 1000 employees worldwide.

Constantinople :

Constantinople is an update of the Ethereum protocol that was implemented via a hard-fork in Block 7 280 000, on February 27, 2019. This update reduces the cost in gas of existing functionalities as well as adding new functionalities on the Blockchain Ethereum. A decrease of the reward per block is also in order with the passage from three to two ethers per block. For more information, you can refer to our article by clicking here.

Cypher Browser :

Cypher Browser is an Ethereum wallet available on Android and IOS allowing the management of Ethereum ethers and tokens.

Difficulty Bomb :

The "difficulty bomb" is a parameter which allows to increase exponentially the difficulty of mining on Ethereum from a certain block number, despite a calculation power which would remain constant on the network. This was put in place in order to remove the economic incentive for miners and force the implementation of the Proof-of-Stake on Ethereum. However, with the delays in the implementation of the PoS, the difficulty bomb has been pushed back several times via the various hard-fork.

EIP - Ethereum Improvement Proposal :

EIPs are proposals to improve the Ethereum Protocol. There is no barrier to entry, which means that anyone can propose an SIP. The community is free to review the SIPs and participate in their refinement. The SITs are then reviewed by the Ethereum Foundation which has the possibility to include them when updating the protocol via a hard fork.

ENS - Ethereum Name Service :

The Ethereum Name Service, as its name indicates, allows you to manage Ethereum domain names. Thus, the domain name coinhousehq.eth is linked to the address 0x010afb8548a5d1a3a3d62f58ca0a5a1329974206. This simplifies the reading and sharing of Ethereum addresses while limiting the risk of error. It is also possible to create sub-domains for a company address, for example davidfaymanzo.coinhousehq.eth. It is also possible via the IPFS network to link this address to a website, for example .


ERC-1155 :

ERC-1155 brings an evolution to the ERC-721 standard. With the latter, it is possible to deploy a contract allowing the generation and use of non-fungible tokens. However, for each type of non-fungible token it is necessary to deploy a different contract. With ERC-1155, it is now possible to generate and manage different types of non-fungible tokens within the same contract.

ERC-1400 :

ERC-1400 defines a multitude of standards for security tokens. These enable tokens to integrate essential functions for the management of financial securities on the Ethereum Blockchain, for example the possibility for a regulator to intervene in the exchanges.

Ethash :

Ethash is the algorithm of Proof-of-Work used in Ethereum. It has been designed to be resistant to ASICs and to promote mining by GPUs.

EVM - Ethereum Virtual Machine :

The Ethereum virtual machine allows anyone to execute the bytecode which defines the contracts. It is an integral part of the Ethereum protocol and thus allows to execute this code in a totally predictable environment without a trusted third party. It is a 256-bit VM Turing-complete of 256 bits.



eWASM is a project under development. It is a new virtual machine using the WebAssembly format for Ethereum. Among its advantages, it is compatible with a wider range of computer languages than EVM, including the C, C++ and Rust libraries. eWASM also aims to significantly increase the speed of contract execution. In addition, Webassembly has a large and active community.

Frontier :

Frontier is the first development phase of the Ethereum network, launched on 30 July 2015. This phase allowed to refine and consolidate the Ethereum protocol as well as to correct bugs in the protocol. It ends with the deployment of Homestead on March 14, 2016.

Geth :

Geth is a command line interface to run an Ethereum node implemented in GB. It is one of the most used implementations of the network.

Github :

Github is the world's largest source code storage platform. It's free and allows any developer to store and update his project. Github is widely used in the cryptocurrency world. Anyone can contribute code for different protocols.

GPU - Graphic Processing Unit :

GPUs are graphics processors that are often integrated into graphics cards. They play an important role in Ethereum as they are used by miners in the mining process.

Homestead :

Homestead was the second phase of the Ethereum protocol deployed on March 14, 2016. Ethereum thus moved from the Frontier phase, a "test" phase only dedicated to developers and considered possibly buggy at Homestead, which was considered a more advanced, stable, and secure network.

Infura :

Infura is a service developed by ConsenSys. It provides the tools necessary for developers of decentralized applications to connect their Dapps to the Ethereum network and the IPFS distributed storage system without having to worry about managing infrastructure operations. Despite Infura's service to the community, some see this as a weakness due to the dependence of many projects on this service.

Joseph Lubin :

Joseph Lubin is a Canadian entrepreneur and one of the important figures in the ecosystem Ethereum. Co-founder of the network, he is today CEO of ConsenSys and fights every day for the success of Ethereum.

Merkle tree :

This is a method of data structure in computing and cryptography, which takes the form of an upside down tree, where the input data represents the leaves and the output data represents the Merkle Root. This is a secure and efficient method of verifying the integrity of a large amount of data. On the network Ethereum, many transactions are streamed. These transactions are drawn from the Memory Pool and are condensed into blocks. Let's assume that our block is composed of 8 transactions, ranging from T1 to T8. These transactions are the leaves of our Merkle tree. Making the Merkle tree of these transactions would produce the hash H1 (from T1 and T2), then the h3 hash (T3 and T4), the h4 hash (T5 and T6) and the H4 hash (T7 and T8). From this, we derive the hash K1 from H1 and h3, then K2 from h4 and H4. We continue according to the same scheme until we obtain the Merkle Root. The Merkle Root represents the final hash condensing the hashes of all the TXIDs of the block (the leaves). In the previous example, the Merkle Root is the hash of K1 and K2.

Metropolis :

Metropolis is the third phase of Ethereum's development after Frontier and Homestead. This phase is deployed in two stages, first with Byzantium and finally with Constantinople.

Multisignature – Multisig :

Refers to a wallet requiring the signature of more than one individual to issue transactions. The use of multisig ranges from the storage of funds raised during a ICO to the sharing of a common account between spouses. This method divides the responsibility for the possession of the funds, and provides more security because a single individual is no longer able to retrieve the funds.

Nonce :

The nonce (abbreviation of Number Used Once) represents the variable data of a block allowing the hash of the block to be less than the current network target. It is any positive integer which, when added to the other fixed components of the block (transactions, the timestamp, the hash of the previous block, etc), results in a hash whose value will be less than the current collective target. In order to find the nonce that will allow the block to be validated, miners must increment it and test each combination. This iterative calculation requires resources and time, making the diffusion of a block with a correct nonce a Proof of Work. The collective target is defined by the difficulty of the network, where the target becomes smaller and smaller (and thus more Proof-of-Work intensive) as the difficulty increases.

Off-chain transactions :

A transaction is characterized Off-Chain when the value movement takes place outside the register of the Blockchain. Unlike an On-chain transaction (a transaction whose result is written into the Blockchain), an Off-chain transaction will not modify the Blockchain and will depend on other methods to verify its validity. The Blockchain then acts as a clearing house.

Parity :

Parity is the most popular implementation of the Ethereum protocol, written in the Rust programming language.

Raiden Network :

The Raiden Network is an overlay network of the Blockchain Ethereum which uses the smart-contracts and the state-channels in order to be able to perform ERC-20 token transactions off-chain. This frees up space in the Blockchain while using it as a clearinghouse with the same level of security. This project is under development.

Serenity :

Serenity is the last phase of development of the Ethereum network after Brontier, Homestead, and Metropolis. Serenity will therefore be the pure version of Ethereum in Proof-of-Stake, stable, and scalable, implementing the advances necessary to fulfill Ethereum's vision and make it a globally adopted technology.

SHA et SHA-256 :

SHA (Secure Hash Algorithm) is a family of cryptographic functions from hashage designed by the NSA, allowing the integrity of data to be determined without the need to consult documents. To do so, the SHA function is able to transform a string of characters of random length (a novel, a photo, a music,...) into a string of characters of fixed length (in this case 256 bits for SHA-256, which represents 64 characters). The slightest change, even minor, to the initial character string has an extremely visible effect on the result of the algorithm: the hash of the modified document is totally different from the hash of the original document.

Sharding :

Sharding is a method of distributing the network load between nodes. Thus, X nodes of the network validate a part of the operations on the Ethereum Blockchain and X other nodes validate another part of the operations. This allows scaling Ethereum because the network is able to process more operations each time X nodes join the network. It is a solution in design but not yet implemented on Ethereum. Casper CBC is a project working on the development of sharding.

Solidity :

Solidity is the most widely used programming language for smart-contracts. It is close to Javascript.

State channels :

A state channel, like a payment channel, allows two users to open a channel and perform transactions off-chain. The difference is that precise rules, in a game run off-chain via a state channel for example, can be defined on-chain to execute a result depending on the actions of the state channel stakeholders.

Timestamp :

The timestamp is one of the components of a block header on the Bitcoin network. It is the number of seconds that have elapsed since January 1, 1970 at 00:00 UTC, commonly known as Unix Time. It is a changing value providing variance for the generation of the hash during the process of mining.

Turing-complete :

Programming languages are called Turing-complete if they allow to represent all calculable functions in the sense of Turing and Church . In particular, this allows the use of loops, which allow the iteration of functions in smart-contracts, which opens up the field of possibilities in terms of application programming. Solidity or Vyper are Turing-complete programming languages.


The TXID is the unique identifier of a transaction.

Uncle blocs :

In the protocol Ethereum blocks of transactions are mined on average every 15.7 seconds. Knowing that it takes a certain amount of time for all the nodes around the world to synchronize with each new block, it is then possible that two miners mining the same block simultaneously broadcast two different versions of the Blockchain to the miners. In this case, there are two states of the Blockchain Ethereum and the miners adding the next block determine which is the correct version of the Blockchain. Thus, one of the two original blocks will not be added to the Blockchain. This is called an Uncle block. Miners are paid less for mining Uncle block, unlike on Bitcoin, where this phenomenon is rarer.

Vyper :

Vyper is a programming language from smart-contract that is gaining popularity. It is very close to the Python language, which is widely appreciated by a large part of the developer community.

Web3 :

Web3 refers to applications that allow users to interact with the Blockchain Ethereum.