Glossary
Overview of Solana/Firedancer-specific terminology.
Account
A record in the account database. Consists of an account address, SOL balance, program owner, and binary data.
Accounts have multiple revisions.
Alpenglow
A major upgrade to the Solana consensus protocol developed by Anza.
Bank
Commonly: A fork graph node corresponding to a Solana block.
A bank object also holds various state required to execute transactions that is not present in the accounts database.
Bundle
A sequence of transactions packed atomically without reordering or interleaving other transactions.
Bundle transactions pay regular Solana fees, with "tips" as an additional incentive for block producers.
Typically delivered via Jito gRPC protocol via the bundle tile.
Chained Merkle Root (CMR)
Uniquely identifies a FEC set and the fork it is on.
Cluster
Synonym for 'Solana network'. E.g. "mainnet-beta cluster".
Consensus
An algorithm all Solana validators in the network run to gain a consistent view of the state of the blockchain (i.e. which fork is canonical and which blocks are finalized).
Duplicate Confirmed
Tower BFT specific. A block is "duplicate confirmed" if 52% of stake weight has voted for it.
Distinct from optimistic confirmation.
Entry
Highly ambiguous, usually synonym of "microblock".
Equivocation
Act of producing two or more conflicting/duplicate blocks at the same slot, produced by the same leader.
Feature
Short for "feature gate", a mechanism used to atomically activate breaking changes or a new feature on a cluster. Typically requires code changes in a validator.
FEC set
Authenticated slice of a block. Multiple FEC sets produce one or more microblocks.
Fork
Sequence of blocks (path in a tree). A fork is uniquely identified by either the block hash, bank hash, or chained merkle root of a slot.
Fork Choice
Algorithm that picks a preferred fork/block given a list of forks and various consensus information (e.g. votes, equivocation proofs).
Gossip
Protocol validators use to propagate cluster state information (such as contact info, votes, and epoch slots) to each other.
Leader
Each Solana network has one leader (a validator) at any given time. The leader changes periodically (every ~1.6 seconds as of May 2026).
Repair
Protocol used to request block data from other validators.
Root / rooting
Synonym of finalization. When a block is rooted, consensus guarantees that this block, its transactions, and state changes are accepted globally and will not be reverted.
RPC
Shorthand for "Solana JSON-RPC", a protocol used to read data and submit transactions.
Snapshot
A file containing a copy of all accounts and bank state as of some rooted slot.
Solfuzz
Application that generates diverse random data (e.g. transactions) with the goal of finding differences in behavior between Firedancer and other validator implementations (e.g. Agave).
Tile
Firedancer operating system thread running a message-passing event loop.
Tiles are usually pinned to CPU cores.
Tower BFT
Original Solana consensus algorithm. Active on mainnet as of May 2026.
Transaction
Usually refers to a Solana transaction, not a database transaction.
Turbine
Protocol used to proactively push block data to other validators.
Validator
Software that replicates all Solana transactions and executes them. Optionally participates in voting and block production.
XDP
Linux kernel API for fast networking.