Canonical Chain
The canonical chain is the sequence of blocks currently accepted by a blockchain’s fork-choice and consensus rules as the authoritative ledger history.…
Crypto & Blockchain Fundamentals
Core concepts behind cryptocurrency, blockchain and distributed systems.
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Terms (367)
Change Output
A change output is a transaction output that returns the unspent remainder of selected UTXOs to an address controlled by the sender.…
Checkpoint Block
A checkpoint block is a block designated by a protocol, validator vote, client rule, or operator policy as a reference point for…
Checksum
A checksum is a value calculated from data and stored or transmitted with it so software can detect many accidental changes during…
Child Block
A child block is a block that directly references another block as its parent and extends that parent’s history by one step.…
Coin Selection
Coin selection is the wallet process of choosing which unspent transaction outputs to use as inputs for a UTXO-based transaction. The choice…
Coinbase Transaction
A coinbase transaction is the special first transaction in a Bitcoin block that creates the block subsidy and assigns it, together with…
Competing Chain
A competing chain is an alternative valid or apparently valid sequence of blocks that conflicts with another branch for the same blockchain…
Compound Transaction
A compound transaction is a transaction that performs several logically connected actions, often across multiple contracts, assets, or account updates, to produce…
Confirmation
A confirmation is evidence that a blockchain transaction has been included in an accepted block and has gained a defined level of…
Confirmation Depth
Confirmation depth is the number of blocks added to a blockchain at or after the block containing a transaction, depending on the…
Confirmation Latency
Confirmation latency is the delay between transaction submission or first observation and the point at which the transaction reaches a specified confirmation…
Confirmation Policy
A confirmation policy is a set of rules that determines when a blockchain transaction is considered sufficiently settled for a business or…
Confirmation Rate
Confirmation rate is a context-dependent metric describing how frequently submitted blockchain transactions become confirmed within a defined period or target time. It…
Confirmation Requirement
A confirmation requirement is the minimum blockchain evidence a system demands before treating a transaction as settled or allowing the next action.…
Confirmation Target
A confirmation target is a desired time, block count, or finality level within which a blockchain transaction should reach an acceptable confirmed…
Confirmation Threshold
A confirmation threshold is the specific minimum level of confirmation or finality that triggers a state change, such as marking a payment…
Confirmation Time
Confirmation time is the elapsed period required for a blockchain transaction to become included and reach a stated confirmation or finality level.…
Confirmation Tracking
Confirmation tracking is the continuous process of following a blockchain transaction after submission or detection to determine its block inclusion, confirmation count,…
Confirmed Block
A confirmed block is a block recognized as part of the currently accepted chain with some defined level of confirmation. The phrase…
Confirmed Nonce
A confirmed nonce is the account transaction sequence value reflected in the canonical confirmed blockchain state. In account-based networks, it usually represents…
Congestion
Congestion occurs when demand for blockchain transaction processing exceeds the capacity available under current block, gas, or execution limits. Pending transactions compete…
Consensus Epoch
A consensus epoch is a protocol-defined period that groups multiple slots, rounds, blocks, or validator duties for consensus accounting. Networks may use…
Consensus Failure
Consensus failure is a condition in which a blockchain cannot maintain its required safety, liveness, or agreement guarantees. It can appear as…