Glossary

Accepting Block

The chain block that merges a given transaction into the VSPC, making the transaction accepted. Transactions inherit their containing block’s acceptance status, and confirmations are counted from the accepting block. See Confirmations & Finality.

Anticone

The blocks that are neither in a given block’s past nor future - typically the result of concurrent creation or block propagation timing. Anticone blocks have ambiguous ordering relative to the given block, which makes the anticone central to GHOSTDAG’s block coloring. See GHOSTDAG Ordering.

Block Coloring

PHANTOM GHOSTDAG classifies all valid blocks as Red or Blue, where color generally indicates how well connected a block is in the DAG. Color dictates a block’s role in consensus, security, and block rewards. See GHOSTDAG Ordering.

Blue Block

A well-connected block, likely mined by an honest node - blue if the number of blue blocks in its anticone is within the k parameter bound. Blue blocks count toward blue score and blue work, and pay the miner. See GHOSTDAG Ordering.

Blue Score

The number of blue blocks in a block’s past: the selected parent’s blue score plus the blue blocks in the block’s mergeset. Feeds confirmation counting and DAA score. See GHOSTDAG Ordering.

Blue Set

The set of blue blocks in the maximum k-Cluster - the largest well-connected subset of honest blocks in the BlockDAG.

Blue Work

The cumulative proof-of-work of all blue blocks in a block’s past; red blocks are excluded. Tip and parent selection are based on blue work. See GHOSTDAG Ordering.

Chain Block

A block in the dynamically chosen subset of blocks forming the backbone of the DAG (the VSPC). Each chain block merges its mergeset into the backbone. See GHOSTDAG Ordering.

Child Block

A block that directly references the given block in its header’s parents field. Child blocks are part of a block’s future.

Compute Mass

A measure quantifying the computational cost of a transaction, calculated over weighted transaction components - signature operations weigh heavily, so multi-sig transactions carry more compute mass. See Units.

Confirmation Count

The number of confirmations a transaction has: sink blue score minus the transaction’s accepting block’s blue score. Grows at roughly 10 per second at 10 BPS. See Confirmations & Finality.

Crescendo Hard Fork

The May 5, 2025 hard fork (activated at DAA score 110,165,000) that moved Kaspa mainnet from 1 to 10 blocks per second, detailed in KIP-0014. See Crescendo Hard Fork.

Covenants

A general concept for a binding agreement between parties, popularized in crypto by proposals to enhance Bitcoin script with opcodes enabling spending conditions on UTXOs.

Covenants++

Also referred to as Cov++ - the set of features comprising Kaspa’s advanced UTXO-based covenant environment. See Covenants++.

DAA Score

The count of blue blocks plus merged & rewarded red blocks - a comprehensive measure of network progress that increases at roughly the block rate. Used for upgrade activations, timestamp estimation, and certain lock times. See Difficulty Adjustment.

DAG

A Directed Acyclic Graph: a data structure of nodes connected by directed edges, with no cycles - it is impossible to leave a node and return to it by following edge directions.

Reference: Directed Acyclic Graph

Deterministic Finality

Finality in which a transaction’s status is guaranteed to never change. Kaspa provides it past the finality depth. See Confirmations & Finality.

Difficulty

A numerical value representing how challenging mining is, relative to the maximum target: difficulty = MAX_DIFFICULTY_TARGET / target. See Difficulty Adjustment.

Difficulty Adjustment Algorithm

The algorithm that adjusts target so actual block production stays at approximately the desired rate (currently 10 BPS). Since the Crescendo hard fork it uses sampled windows (KIP-0004) instead of full windows. See Difficulty Adjustment.

Effective TPS (e-TPS)

A measure of DAG capacity utilization relative to available mempool transactions. 1.0 means throughput is handling current demand; 0.0 means capacity is largely filled with duplicate transactions despite unique transactions waiting.

Reference: e_tps in rusty-kaspa

Fee Rate

The multiplier used to calculate a transaction’s fee, in sompi per gram of mass: fee = fee rate × mass. The GetFeeEstimate RPC returns priority / normal / low buckets targeting sub-second / sub-minute / sub-hour DAG inclusion. See Units: Fees.

Finality

The point at which a transaction is considered irreversible - as a probability (probabilistic) or a guarantee (deterministic). Kaspa has probabilistic finality plus a finality depth providing deterministic finality. See Confirmations & Finality.

Finality Depth

The depth past which blocks and their transactions become deterministically final - approximately 12 hours (24 hours before Crescendo). Exists primarily to make pruning safe. See Confirmations & Finality.

Future

The blocks that a given block is reachable from, via direct or indirect reference. Future blocks are provably created after the given block.

Hash Rate

The total computational power mining on the network - the rate at which miners generate hashes. Calculable as difficulty × 2 × BPS. See Difficulty Adjustment.

k-Cluster

A subset of the BlockDAG where no block has an anticone larger than k within the subset - a set where nearly every pair of blocks has a clear ordering relationship. See GHOSTDAG Ordering.

k Parameter

The number bounding the maximum anticone size for inclusion in a k-cluster. See GHOSTDAG Ordering.

Lock Time

An optional transaction field specifying the earliest point a transaction can be included in a block: 0 means immediately eligible, values below 500 billion are a minimum DAA score, and values of 500 billion or above are a minimum Unix timestamp in milliseconds.

Mergeset

The set of blocks a given block merges into the DAG: blocks in its past, but not in the past of its selected parent. See GHOSTDAG Ordering.

Parent Blocks

The blocks referenced in the parents field of a block’s header. When a block is mined, all known DAG tips are referenced as parents.

Past

All blocks reachable from a given block, via direct parent references or by following edges. See Also: Future

Probabilistic Finality

Finality in which the probability of reversal decreases exponentially as subsequent blocks are mined - never exactly zero, but quickly negligible. See Confirmations & Finality.

Pruning

Kaspa nodes by default discard block data older than approximately 30 hours to keep node hardware requirements low; the UTXO set is retained completely. Archival nodes keep everything. See Pruning.

Real Time Decentralization (RTD)

A Kaspa-specific concept popularized by Yonatan Sompolinsky: a network’s ability to sample the honest majority of miners in real time - within roughly one internet round-trip (~1 second or less) - to determine consensus.

Red Block

A poorly connected block - one whose anticone contains more blue blocks than the k parameter allows. Red blocks are valid and merged into the DAG, but their miners are penalized: rewards go to the merging blue block’s miner, or are not paid at all. See GHOSTDAG Ordering.