Terminology

The following terms are used throughout the Solana documentation and development ecosystem.

account

A record in the Solana ledger that either holds data or is an executable program.

Like an account at a traditional bank, a Solana account may hold funds called lamports. Like a file in Linux, it is addressable by a key, often referred to as a public key or pubkey.

The key may be one of:

an ed25519 public key
a program-derived account address (32byte value forced off the ed25519 curve)
a hash of an ed25519 public key with a 32 character string

account owner

The address of the program that owns the account. Only the owning program is capable of modifying the account.

app

A front-end application that interacts with a Solana cluster.

authority

The address of a user that has some kind of permission over an account.

For example:

The ability to mint new tokens is given to the account that is the 'mint authority' for the token mint.
The ability to upgrade a program is given to the account that is the 'upgrade authority' of a program.

bank state

The result of interpreting all programs on the ledger at a given tick height. It includes at least the set of all accounts holding nonzero native tokens.

block

A contiguous set of entries on the ledger covered by a vote. A leader produces at most one block per slot.

blockhash

A unique value (hash) that identifies a record (block). Solana computes a blockhash from the last entry id of the block.

block height

The number of blocks beneath the current block. The first block after the genesis block has height one.

bootstrap validator

The validator that produces the genesis (first) block of a block chain.

BPF loader

The Solana program that owns and loads BPF onchain programs, allowing the program to interface with the runtime.

client

A computer program that accesses the Solana server network cluster.

commitment

A measure of the network confirmation for the block.

cluster

A set of validators maintaining a single ledger.

compute budget

The maximum number of compute units consumed per transaction.

compute units

The smallest unit of measure for consumption of computational resources of the blockchain.

confirmation time

The wallclock duration between a leader creating a tick entry and creating a confirmed block.

confirmed block

A block that has received a super majority of ledger votes.

control plane

A gossip network connecting all nodes of a cluster.

Some number of epochs after stake has been deactivated while it progressively becomes available for withdrawal. During this period, the stake is considered to be "deactivating". More info about: warmup and cooldown

credit

See vote credit.

cross-program invocation (CPI)

A call from one onchain program to another. For more information, see calling between programs.

data plane

A multicast network used to efficiently validate entries and gain consensus.

drone

An offchain service that acts as a custodian for a user's private key. It typically serves to validate and sign transactions.

entry

An entry on the ledger either a tick or a transaction's entry.

entry id

A preimage resistant hash over the final contents of an entry, which acts as the entry's globally unique identifier. The hash serves as evidence of:

The entry being generated after a duration of time
The specified transactions are those included in the entry
The entry's position with respect to other entries in ledger

See proof of history.

epoch

The time, i.e. number of slots, for which a leader schedule is valid.

fee account

The fee account in the transaction is the account that pays for the cost of including the transaction in the ledger. This is the first account in the transaction. This account must be declared as Read-Write (writable) in the transaction since paying for the transaction reduces the account balance.

finality

When nodes representing 2/3rd of the stake have a common root.

fork

A ledger derived from common entries but then diverged.

genesis block

The first block in the chain.

genesis config

The configuration file that prepares the ledger for the genesis block.

hash

A digital fingerprint of a sequence of bytes.

inflation

An increase in token supply over time used to fund rewards for validation and to fund continued development of Solana.

inner instruction

See cross-program invocation.

instruction

A call to invoke a specific instruction handler in a program. An instruction also specifies which accounts it wants to read or modify, and additional data that serves as auxiliary input to the instruction handler. A client must include at least one instruction in a transaction, and all instructions must complete for the transaction to be considered successful.

instruction handler

Instruction handlers are program functions that process instructions from transactions. An instruction handler may contain one or more cross-program invocations.

keypair

A public key and corresponding private key for accessing an account.

lamport

A fractional native token with the value of 0.000000001 sol.

Within the compute budget, a quantity of micro-lamports is used in the calculation of prioritization fees.

leader

The role of a validator when it is appending entries to the ledger.

leader schedule

A sequence of validator public keys mapped to slots. The cluster uses the leader schedule to determine which validator is the leader at any moment in time.

ledger

A list of entries containing transactions signed by clients. Conceptually, this can be traced back to the genesis block, but an actual validator's ledger may have only newer blocks to reduce storage, as older ones are not needed for validation of future blocks by design.

ledger vote

A hash of the validator's state at a given tick height. It comprises a validator's affirmation that a block it has received has been verified, as well as a promise not to vote for a conflicting block (i.e. fork) for a specific amount of time, the lockout period.

light client

A type of client that can verify it's pointing to a valid cluster. It performs more ledger verification than a thin client and less than a validator.

loader

A program with the ability to interpret the binary encoding of other onchain programs.

lockout

The duration of time for which a validator is unable to vote on another fork.

message

The structured contents of a transaction. Generally containing a header, array of account addresses, recent blockhash, and an array of instructions.

Learn more about the message formatting inside of transactions here.

Nakamoto coefficient

A measure of decentralization, the Nakamoto Coefficient is the smallest number of independent entities that can act collectively to shut down a blockchain. The term was coined by Balaji S. Srinivasan and Leland Lee in Quantifying Decentralization.

native token

The token used to track work done by nodes in a cluster.

node

A computer participating in a cluster.

node count

The number of validators participating in a cluster.

onchain program

The executable code on Solana blockchain that interprets the instructions sent inside of each transaction to read and modify accounts over which it has control. These programs are often referred to as "smart contracts" on other blockchains.

PoH

See Proof of History.

point

A weighted credit in a rewards regime. In the validator rewards regime, the number of points owed to a stake during redemption is the product of the vote credits earned and the number of lamports staked.

private key

The private key of a keypair.

program

See onchain program.

program derived account (PDA)

An account whose signing authority is a program and thus is not controlled by a private key like other accounts.

program id

The public key of the account containing a program.

proof of history (PoH)

A stack of proofs, each of which proves that some data existed before the proof was created and that a precise duration of time passed before the previous proof. Like a VDF, a Proof of History can be verified in less time than it took to produce.

prioritization fee

An additional fee user can specify in the compute budget instruction to prioritize their transactions.

The prioritization fee is calculated by multiplying the requested maximum compute units by the compute-unit price (specified in increments of 0.000001 lamports per compute unit) rounded up to the nearest lamport.

Transactions should request the minimum amount of compute units required for execution to minimize fees.

public key (pubkey)

The public key of a keypair.

rent

Fee paid by Accounts and Programs to store data on the blockchain. When accounts do not have enough balance to pay rent, they may be Garbage Collected.

See also rent exempt below. Learn more about rent here: What is rent?.

rent exempt

Accounts that maintain a minimum lamport balance that is proportional to the amount of data stored on the account. All newly created accounts are stored on-chain permanently until the account is closed. It is not possible to create an account that falls below the rent exemption threshold.

root

A block or slot that has reached maximum lockout on a validator. The root is the highest block that is an ancestor of all active forks on a validator. All ancestor blocks of a root are also transitively a root. Blocks that are not an ancestor and not a descendant of the root are excluded from consideration for consensus and can be discarded.

runtime

The component of a validator responsible for program execution.

Sealevel

Solana's parallel run-time for onchain programs.

shred

A fraction of a block; the smallest unit sent between validators.

signature

A 64-byte ed25519 signature of R (32-bytes) and S (32-bytes). With the requirement that R is a packed Edwards point not of small order and S is a scalar in the range of 0 <= S < L. This requirement ensures no signature malleability. Each transaction must have at least one signature for fee account. Thus, the first signature in transaction can be treated as transaction id

skip rate

The percentage of skipped slots out of the total leader slots in the current epoch. This metric can be misleading as it has high variance after the epoch boundary when the sample size is small, as well as for validators with a low number of leader slots, however can also be useful in identifying node misconfigurations at times.

skipped slot

A past slot that did not produce a block, because the leader was offline or the fork containing the slot was abandoned for a better alternative by cluster consensus. A skipped slot will not appear as an ancestor for blocks at subsequent slots, nor increment the block height, nor expire the oldest recent_blockhash.

Whether a slot has been skipped can only be determined when it becomes older than the latest rooted (thus not-skipped) slot.

slot

The period of time for which each leader ingests transactions and produces a block.

Collectively, slots create a logical clock. Slots are ordered sequentially and non-overlapping, comprising roughly equal real-world time as per PoH.

smart contract

See onchain program.

SOL

The native token of a Solana cluster.

Solana Program Library (SPL)

A library of programs on Solana such as spl-token that facilitates tasks such as creating and using tokens.

stake

Tokens forfeit to the cluster if malicious validator behavior can be proven.

stake-weighted quality of service (SWQoS)

SWQoS allows preferential treatment for transactions that come from staked validators.

supermajority

2/3 of a cluster.

sysvar

A system account. Sysvars provide cluster state information such as current tick height, rewards points values, etc. Programs can access Sysvars via a Sysvar account (pubkey) or by querying via a syscall.

thin client

A type of client that trusts it is communicating with a valid cluster.

tick

A ledger entry that estimates wallclock duration.

tick height

The Nth tick in the ledger.

token

A digitally transferable asset.

Token Extensions Program

The Token Extensions Program has the program ID TokenzQdBNbLqP5VEhdkAS6EPFLC1PHnBqCXEpPxuEb and includes all the same features as the Token Program, but comes with extensions such as confidential transfers, custom transfer logic, extended metadata, and much more.

Terminology

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