Glossary and General Definitions


In blockchain technology, a block is a collection of data that represents a set of transactions. It is the fundamental unit in a blockchain, containing a list of transactions, a timestamp, and a reference to the previous block, forming a chain of blocks. Each block is linked to the previous one, creating an immutable and chronological ledger of transactions.

Block Explorer

A block explorer is a web-based tool or interface that allows users to explore and navigate a blockchain. It provides real-time information about transactions, blocks, addresses, and other relevant data on a blockchain network. Block explorers are commonly used to track the progress of transactions, verify the status of a payment, and explore the history of a particular blockchain.

Block Height

Block height refers to the number of blocks in a blockchain from the genesis block (the first block in the chain) up to a specific block. It is a way to measure the chronological order of blocks in the blockchain. For example, if a block has a height of 1000, it means it is the 1000th block in the blockchain.

Block Reward

The block reward is a form of incentive for participants in a blockchain network, especially miners, who contribute computing power to validate and add new blocks to the blockchain. When a miner successfully adds a new block, they are rewarded with a certain amount of cryptocurrency. This reward typically consists of newly created cryptocurrency coins (or tokens) and transaction fees from the transactions included in the block.

Cold Storage

Cold storage refers to keeping a reserve of cryptocurrency offline, not connected to the internet. This is done to enhance the security of the cryptocurrency holdings by reducing the risk of cyber attacks and unauthorized access. Cold storage methods include hardware wallets, paper wallets, or other physical devices that store the private keys needed to access the cryptocurrency. It contrasts with "hot wallets" that are connected to the internet, such as those on exchanges, which are more vulnerable to hacking attempts.


In the context of cryptocurrency, a token is a digital asset or unit of value issued and managed on a blockchain. Tokens can represent various assets, rights, or utilities and are often created through a smart contract on a blockchain platform.


A coin is a digital or virtual currency that operates on its own independent blockchain. Coins are native to their respective blockchain and serve as a medium of exchange within that particular network.


Confirmations in the context of cryptocurrency refer to the number of times a transaction has been validated and added to the blockchain. The more confirmations a transaction has, the more secure and irreversible it becomes.

Contract Address

A contract address is a unique identifier assigned to a smart contract on a blockchain. It is an address to which users can send transactions to interact with the functions and logic encoded in the smart contract.

Decentralized Service

A decentralized service is a service or application that operates on a decentralized network or blockchain. It means that the service doesn't rely on a single central authority or server for its operation, enhancing transparency, security, and censorship resistance.

Destination Tag

A destination tag is a unique identifier used in some cryptocurrency transactions, particularly in networks like Ripple (XRP) or Stellar (XLM). It helps direct funds to the correct recipient when multiple users share the same deposit address.

ERC-20 Token

ERC-20 stands for Ethereum Request for Comment 20 and is a standard for fungible tokens on the Ethereum blockchain. These tokens are created and managed according to specific rules, allowing them to be easily traded and interact with other smart contracts on the Ethereum network.

Exchange Rate

The exchange rate is the value of one cryptocurrency or fiat currency in terms of another. It represents the relative value of one currency or asset compared to another and is a crucial factor in trading and investment decisions.


Fiat currency is government-issued currency that is not backed by a physical commodity like gold or silver. Examples include the US Dollar (USD), Euro (EUR), and Japanese Yen (JPY). Fiat currencies are the traditional forms of money used for daily transactions.


A fork in the context of blockchain technology refers to a divergence in the blockchain's protocol, leading to the creation of two separate chains. Forks can be categorized as hard forks (irreversible split) or soft forks (backward-compatible).

Genesis Block

The genesis block is the first block in a blockchain. It serves as the foundation of the entire blockchain and often contains unique information or code that distinguishes it from subsequent blocks.


Gwei is a denomination of the cryptocurrency Ethereum (ETH) and represents a unit of gas, which is used to calculate transaction fees on the Ethereum network. It is named after Wei Dai, a computer scientist and cryptographer.

Hot Wallet

A hot wallet is a cryptocurrency wallet that is connected to the internet. It is used for actively transacting and trading cryptocurrencies. Hot wallets are more susceptible to hacking attempts compared to cold storage solutions.

Key Pairs

Key pairs in cryptography consist of a public key and a private key. These pairs are used in asymmetric (or public-key) cryptography, where the public key is shared openly, and the private key is kept secret. Cryptographic operations, such as encryption and digital signatures, rely on key pairs.

Legacy Address

A legacy address refers to the traditional address format used in cryptocurrencies like Bitcoin. It is typically a base58 or base58check encoded string. Legacy addresses are still in use but have been largely replaced by newer address formats like Segregated Witness (SegWit) addresses.


The mempool (short for memory pool) is a temporary storage area for unconfirmed transactions in a cryptocurrency network. Miners select transactions from the mempool to include in the next block they mine. Transactions in the mempool are waiting to be added to the blockchain.

Miner Fee

A miner fee is a small amount of cryptocurrency paid to miners for including a transaction in a block. It serves as an incentive for miners to prioritize a particular transaction. The higher the fee, the more likely a miner is to include the transaction promptly.


Multisignature (multisig) refers to a type of cryptocurrency address and transaction that requires multiple private keys to authorize a transaction. It enhances security by distributing control among multiple parties, and a predetermined number of signatures is required for transaction validation.

Payment ID

A payment ID is a unique identifier used in some cryptocurrency transactions, especially in privacy-focused coins. It helps distinguish between different payments sent to the same address. Payment IDs are crucial when using exchanges or services that share a common deposit address.


Phishing is a cyber-attack where malicious actors attempt to deceive individuals into revealing sensitive information, such as private keys or login credentials. Phishing often involves fake websites or communication designed to mimic legitimate ones.

Private Key

A private key is a secret cryptographic key known only to the owner. It is used to sign transactions, providing mathematical proof of ownership. Safeguarding the private key is crucial for protecting one's cryptocurrency holdings.

Public Key

A public key is derived from a private key and is openly shared. It is used to generate a public address to receive cryptocurrency. While the public key can be shared openly, the private key must remain confidential.

Refund Address

A refund address is an address provided by the recipient to return funds in case of an unsuccessful or canceled transaction. It is a safety measure to ensure that funds can be returned to the sender in specific situations.

Replay Attack

A replay attack is a type of attack where a valid transaction is intercepted and maliciously re-broadcast on a different network or blockchain. It can lead to unintended consequences and is often a concern during network upgrades or forks.

Transaction Fee

A transaction fee is the amount paid by users to process and validate their cryptocurrency transactions. It is collected by miners and acts as an incentive for them to include the transaction in a block.


TXID (Transaction ID) or hash is a unique identifier generated for each cryptocurrency transaction. It is a string of characters obtained through cryptographic hashing and serves as a reference to the specific transaction.


Unspent Transaction Output (UTXO) refers to the portion of cryptocurrency that has been sent and is available to be spent. Each transaction creates new UTXOs, and spent UTXOs cannot be used again.


A whitepaper is a detailed document that provides information about the technology, purpose, and features of a cryptocurrency or blockchain project. It typically outlines the problem the project aims to solve, the proposed solution, and technical details.

Withdrawal Address

A withdrawal address is the recipient address specified when a user initiates the withdrawal of cryptocurrency from an exchange or wallet. It is the destination where the withdrawn funds will be sent.