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Education-only blockchain explanations
A to Z glossary Education-only Source-led terms

Blockchain and digital asset technology glossary.

Definitions on this page explain concepts, not financial actions. We avoid trading language and do not recommend buying, selling, or exchanging any digital asset.

How to use this glossary
  • Look for “What it is” and “What it is not” to reduce confusion.
  • Use the “Related terms” line to build a mental map across topics.
  • For deeper reading, see Topics and Guides.
Last updated: • Author: Omar Siddiqui • Editorial owner: Hannah Reed

Glossary index

Quick navigation to common terms. This page does not include price discussion, market analysis, or recommendations.

A B C D F G H L M N P S T V W
alphabetical glossary cards with blockchain terms in midnight navy and electric blue

Definitions (selected core terms) 📘

These definitions are written for general understanding. Where a term has multiple meanings across different ecosystems, we describe the common baseline meaning and note variations.

A

Glossary section
Term

Address (blockchain address)

What it is: A string of characters that identifies an account or destination on a blockchain network (often derived from a public key, depending on the system).
What it is not: A bank account number, and not proof of identity on its own.
Related terms: public key, private key, wallet, transaction.
Term

Audit (smart contract audit)

What it is: A review process that aims to identify security issues or correctness problems in smart contract code, usually with a written report.
What it is not: A guarantee that software is bug-free or safe in all circumstances.
Related terms: smart contract, vulnerability, threat model.

B

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Term

Block

What it is: A batch of data that a blockchain adds to its history, commonly including transactions and metadata like timestamps and references to earlier blocks.
What it is not: A single transaction, and not automatically “final” in all systems until the network’s finality rules are met.
Related terms: chain, transaction, finality, fork.
Term

Bridge (cross-chain bridge)

What it is: A mechanism that enables assets or messages to move between two blockchain networks, usually by locking or verifying state on one side and minting or releasing on the other.
What it is not: A guarantee of security. Bridges can introduce new trust assumptions and failure modes.
Related terms: wrapped token, validator, proof, custody.

C

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Term

Consensus mechanism

What it is: The rules and protocol by which a decentralised network agrees on a shared state (for example, which transactions are included and in what order).
What it is not: A single technology. “Consensus” can involve multiple components like networking, cryptography, and incentives.
Related terms: node, validator, finality, fork.
Term

Custody

What it is: Who controls the keys needed to authorise transactions. “Self-custody” typically means the user controls the private keys; “third-party custody” means another entity controls keys on the user’s behalf.
What it is not: A guarantee of safety. Each custody model has different risks and responsibilities.
Related terms: private key, seed phrase, wallet.

D

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Decentralisation

What it is: A design property where control and decision-making are distributed across multiple participants rather than a single central operator.
What it is not: A binary state. Networks can be more or less decentralised depending on governance, infrastructure concentration, and client diversity.
Related terms: node, governance, validator set.
Term

Distributed ledger

What it is: A record of data that is replicated across multiple machines and kept in sync using agreed rules. A blockchain is one type of distributed ledger.
What it is not: Always permissionless. Some ledgers are run by a closed set of known participants.
Related terms: blockchain, consensus, node.

F

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Term

Finality

What it is: The point at which a transaction or block is considered effectively irreversible under the network’s rules (for example, after sufficient confirmations or after a finality gadget).
What it is not: Always instantaneous. Different systems provide different finality properties.
Related terms: confirmation, fork, consensus.
Term

Fork

What it is: A divergence in a blockchain’s history or rules. Forks can be temporary (two competing branches) or rule-changing (a protocol update).
What it is not: Automatically a security incident. Some forks are normal parts of consensus and upgrades.
Related terms: finality, consensus, upgrade.

G

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Term

Gas (transaction fee unit)

What it is: A unit that represents computational work on some smart contract platforms. Users pay fees based on how much work their transaction requires and network conditions.
What it is not: A “service fee” set by a single operator. Fee mechanisms vary by protocol design.
Related terms: transaction, block, smart contract, mempool.
Term

Genesis block

What it is: The first block in a blockchain’s history. It is often hard-coded into the software clients that participate in the network.
What it is not: A special permission for later changes. Subsequent rules are determined by the protocol and community processes.
Related terms: chain, block header, client software.

H

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Hash (cryptographic hash)

What it is: The output of a cryptographic function that maps input data to a fixed-size value. Small input changes produce very different outputs.
What it is not: Encryption. A hash is not designed to be reversed back into the original data.
Related terms: block header, Merkle tree, integrity.
Term

Hardware wallet

What it is: A device designed to keep private keys isolated from general-purpose computers. It typically signs transactions inside the device.
What it is not: A “storage location” for coins. Keys control authorisation; assets remain on the network ledger.
Related terms: private key, seed phrase, signing.

L

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Term

Layer 1 (L1)

What it is: The base blockchain network where transactions are ultimately recorded and validated according to the protocol’s consensus rules.
What it is not: A performance guarantee. Different L1s have different trade-offs across security, throughput, and decentralisation.
Related terms: rollup, sidechain, finality.
Term

Liquidity (technical meaning)

What it is: In market microstructure, a measure of how easily an asset can be exchanged without significant price impact. In blockchain product design, it can also refer to how readily a token can be exchanged on a given venue.
What it is not: A promise about outcomes. This glossary does not provide guidance on trading or market decisions.
Related terms: exchange, order book, slippage (conceptual).

M

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Term

Mempool

What it is: A node’s queue of valid, unconfirmed transactions that may be included in future blocks. Different nodes can have slightly different mempools.
What it is not: A single shared database that all participants see identically.
Related terms: transaction, block, fee mechanism.
Term

Merkle tree

What it is: A data structure that groups and hashes data in layers, enabling efficient proofs that a given item is included in a larger set.
What it is not: A privacy tool by itself. It is primarily about integrity and efficient verification.
Related terms: hash, proof, block header.

N

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Term

Node

What it is: A computer running software that participates in a blockchain network, often by validating data and relaying information to peers.
What it is not: Always the same as a miner or validator. Roles vary by network design.
Related terms: client, validator, consensus.
Term

NFT (non-fungible token)

What it is: A token that typically represents a unique identifier on a blockchain, often linked to metadata. “Non-fungible” means one unit is not interchangeable with another unit in the way a standard currency unit is.
What it is not: Automatically ownership of an underlying asset or IP rights. Rights depend on off-chain agreements and applicable law.
Related terms: token standard, metadata, smart contract.

P

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Term

Private key

What it is: A secret value used to create digital signatures that authorise actions (for example, sending a transaction) in systems based on public-key cryptography.
What it is not: A password you can reset with a helpdesk. If it is lost or exposed, control can be affected depending on the system.
Related terms: public key, signature, seed phrase, custody.
Term

Public key

What it is: A value derived from a private key that can be shared publicly. It is used to verify signatures and, in many systems, to derive an address.
What it is not: Proof of identity. It is a cryptographic identifier, not a government-issued credential.
Related terms: private key, address, signature.

S

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Term

Seed phrase (recovery phrase)

What it is: A sequence of words that can be used to regenerate private keys for a wallet, depending on the wallet’s standard (often based on mnemonic schemes).
What it is not: A username. Anyone with the phrase can potentially control associated keys, so it must be protected.
Related terms: private key, wallet, custody.
Term

Smart contract

What it is: A program deployed to a blockchain that can execute deterministic logic when called, updating state according to predefined rules.
What it is not: A legal contract by default. Legal enforceability depends on jurisdiction and the surrounding agreement.
Related terms: token standard, audit, gas, state.
Term

Stablecoin

What it is: A digital token that aims to maintain a relatively stable reference value (often linked to a fiat currency) through a specific design, such as reserve-backed issuance or algorithmic mechanisms.
What it is not: A guarantee of stability. Stability depends on design, governance, reserve quality (if any), and market structure.
Related terms: reserves, collateral, redemption model, settlement.

T

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Term

Token standard

What it is: A commonly adopted interface for tokens on a given platform, enabling wallets, explorers, and apps to interact with tokens consistently.
What it is not: A regulatory classification. “Standard” refers to technical interoperability, not legal status.
Related terms: smart contract, metadata, NFT.
Term

Transaction

What it is: A signed message that requests a state change on a blockchain, such as transferring a token or calling a smart contract function.
What it is not: An instant final record. Transactions may remain pending until included in a block and considered final under network rules.
Related terms: signature, mempool, block, finality.

V

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Term

Validator

What it is: A participant that helps propose or attest to blocks and enforces protocol rules, commonly associated with Proof-of-Stake style designs.
What it is not: A regulator or authority. A validator follows network rules but does not confer legal approval.
Related terms: consensus, finality, node.
Term

Volatility

What it is: A measure of how much prices can change over time. In digital assets, volatility is often high and can be influenced by liquidity, sentiment, and market structure.
What it is not: A forecast. This site does not publish price predictions or trading guidance.
Related terms: liquidity, stablecoin (design goal), risk.

W

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Term

Wallet

What it is: Software or hardware that manages keys and helps users create and sign transactions, display balances, and interact with applications.
What it is not: A container where assets “live.” Assets are recorded on the blockchain; wallets manage authorisation via keys.
Related terms: private key, seed phrase, custody, address.
Term

Wrapped token

What it is: A representation of an asset from one chain on another chain, usually backed by a custody or verification mechanism that supports minting and redemption.
What it is not: The original asset itself. The wrapped token inherits assumptions about the wrapping mechanism and its security.
Related terms: bridge, custody, proof.

Education-only disclaimer (quick reminder)

Content is provided for educational purposes only. Nothing on the website constitutes financial, investment, tax, or legal advice. Digital assets are volatile and involve risk. Regulations differ by country. No investment recommendations are provided.

Read full disclaimer How we define terms

Sources and references 🔎

This glossary is compiled from widely used technical definitions and documentation patterns. For policy-sensitive terminology and UK context, we prioritise regulator and standards material where relevant.

Primary documentation
  • Protocol client documentation (consensus, networking, and data structures).
  • Standards repositories and interface specifications for token standards.
Security and operations
  • Security advisories and responsible disclosure write-ups.
  • Wallet safety and threat-model language commonly used in audits.

Note: We do not provide links to exchanges, price tools, trading platforms, or investment products.