RPC and blockchain glossary
Last updated:
| Term | Chains | Definition |
|---|---|---|
| ABI (application binary interface) | EVM chains | The Contract Application Binary Interface (ABI) is the standard way to interact with contracts in the Ethereum ecosystem, from outside the chain and between contracts. |
| ADNL (TON) | TON | ADNL (Abstract Datagram Network Layer) is TON's network protocol; ADNL over TCP is used by clients to communicate with liteservers. |
| Archive node | All chains | An archive node retains the full historical state of the chain, so it can answer state queries at any past block, not only near the head. |
| Associated token account (ATA) | Solana | An associated token account (ATA) is the canonical SPL token account for one wallet and one mint, located at an address derived from the wallet address, the token program and the mint. |
| Base fee (EIP-1559) | EVM chains | The base fee is the minimum price per unit of gas, set by the protocol for each block under EIP-1559; it is burned rather than paid to the block producer. |
| Block height | All chains | Block height is the number of blocks beneath a block in its chain — its position in the sequence of produced blocks, counted from genesis. |
| Block tag | EVM chains | A block tag is a named block parameter in Ethereum JSON-RPC — earliest, latest, safe, finalized or pending — used instead of a block number. |
| Bounceable address (TON) | TON | A bounceable address is a TON user-friendly address whose flag asks the sender to set the bounce flag, so a message returns its value if the destination cannot process it. |
| Chain ID | EVM chains | A chain ID is a number that identifies an EVM chain and is included in every transaction signature under EIP-155, so a transaction signed for one chain is invalid on another. |
| Chain reorganization (reorg) | All chains | A chain reorganization (reorg) happens when a node switches its view of the chain head to a competing branch, replacing one or more of its most recent blocks. |
| Commitment level | Solana | A commitment level tells a Solana RPC node how settled the state it reads must be: processed, confirmed or finalized. |
| Compute unit (Solana) | Solana | A compute unit is the smallest unit of measure for consumption of computational resources on Solana. |
| Energy and bandwidth (TRON) | Tron | Bandwidth and energy are TRON's two transaction resources: bandwidth pays for the bytes a transaction occupies, and energy pays for smart-contract execution. |
| EOA vs contract account | EVM chains | An externally owned account (EOA) is controlled by whoever holds its private key; a contract account is a deployed smart contract controlled by its code. |
| Epoch (Solana) | Solana | An epoch is the number of slots for which a Solana leader schedule is valid. |
| Event log | EVM chains | An event log is a record emitted by an EVM contract during a transaction, made of the emitting address, up to four topics and a data field, and stored in the transaction's receipt. |
| Event topic | EVM chains | A topic is one of up to four 32-byte indexed fields of an EVM event log; topic 0 is normally the keccak-256 hash of the event's canonical signature. |
| Finality | All chains | Finality is the point after which a block — and every transaction in it — can no longer be reverted by the network's consensus rules. |
| Fork | All chains | A fork is a ledger derived from common entries that then diverged from another. |
| Gas | EVM chains | Gas is the unit that measures the computational work an EVM transaction performs; the sender pays for the gas used at a price per unit. |
| History retention window | All chains | A history retention window is the range of past blocks, ledgers or state a particular node still keeps and can answer from. |
| Horizon (Stellar) | Stellar | Horizon is the REST API server for the Stellar network: it serves accounts, payments, operations, effects, ledgers and transactions as HAL JSON. |
| JSON-RPC | All chains | JSON-RPC 2.0 is a stateless remote-procedure-call protocol that encodes a request as a JSON object with jsonrpc, method, params and id, and answers with either a result or an error. |
| Lamport | Solana | A lamport is a fractional unit of Solana's native token, with the value of 0.000000001 SOL. |
| Layer 2 rollup | Base and other L2s | A rollup is a layer 2 that performs transaction execution outside layer 1 and posts the data to layer 1, where consensus is reached. |
| Leader and leader schedule (Solana) | Solana | The leader is the role of a Solana validator while it appends entries to the ledger; the leader schedule is the sequence of validator public keys mapped to slots. |
| Ledger (Stellar) | Stellar | A ledger is a representation of the state of the Stellar network at a given point in time, shared across all network nodes. |
| Liteserver (TON) | TON | A liteserver is a TON full node that serves blockchain data to lite clients over the ADNL protocol, answering queries about blocks, accounts and transactions. |
| Logical time (TON) | TON | Logical time (lt) is a counter carried by every TON transaction that strictly increases with each new transaction of the account. |
| Masterchain (TON) | TON | The masterchain is TON's workchain -1, which holds global configuration and system smart contracts. |
| Mempool (transaction pool) | EVM chains | A mempool (transaction pool) is the set of valid, not-yet-included transactions a node holds and relays while they wait to be put into a block. |
| Merkle proof (eth_getProof) | EVM chains | A Merkle proof is the list of trie nodes along the path from a state root to an account or storage slot, enough to verify that value without the full state. |
| Muxed account (Stellar) | Stellar | A muxed account combines a Stellar G… account with a 64-bit integer ID into an M… address; it does not exist on the ledger, only its underlying G account does. |
| Node sync status | All chains | A node's sync status says whether it has caught up with the chain head or is still importing blocks. |
| Nonce (account nonce) | EVM chains | An account nonce is the number of transactions an externally owned account has had included on chain; each new transaction must carry exactly the next nonce. |
| Pagination cursor | All chains | A pagination cursor is an opaque marker of a position in an ordered result list; passing it back asks the API for the records after (or before) that position. |
| Preflight simulation (Solana) | Solana | Preflight is the set of checks Solana's sendTransaction runs before forwarding a transaction: signature verification, blockhash recency and a simulation. |
| Priority fee | Solana, EVM chains | A priority fee is an optional amount paid on top of a network's base fee to make a transaction more attractive to include. |
| Program derived address (PDA) | Solana | A program derived address (PDA) is a Solana address derived deterministically from a program ID and a set of seeds, chosen so that it has no corresponding private key and only the program can sign for it. |
| Rate limit (HTTP 429) | All chains | A rate limit caps how many requests a client may send in a given amount of time; exceeding it returns HTTP 429 Too Many Requests. |
| Raw (signed) transaction | EVM chains | A raw transaction is a transaction that has already been signed and serialized by the sender, submitted to a node as bytes. |
| Recent blockhash (Solana) | Solana | A blockhash is a unique hash that identifies a Solana block; every transaction includes a recent one, which limits how long the transaction stays valid. |
| Rent exemption (Solana) | Solana | Rent exemption is the minimum lamport balance a Solana account must hold, in proportion to its data size, to stay on-chain. |
| Sequence number (Stellar) | Stellar | A Stellar sequence number identifies and verifies the order of transactions from a source account; each transaction must use the account's stored sequence number plus one. |
| Sequencer (L2) | Base and other L2s | A sequencer is the component of a layer 2 rollup that orders incoming transactions and produces the rollup's blocks. |
| Server-Sent Events (SSE) | Stellar, all chains | Server-Sent Events (SSE) let a server push messages to a client over one long-lived HTTP response with the text/event-stream type; the channel is one-way, server to client. |
| Shred (Solana) | Solana | A shred is a fraction of a Solana block — the smallest unit sent between validators. |
| Slot | Solana | A slot is the period of time for which a Solana leader ingests transactions and produces a block. A slot that did not produce a block — because the leader was offline or its fork was abandoned — is a skipped slot. |
| Solidified block (TRON) | Tron | A solidified block is a TRON block that has become irreversible because at least 19 of the 27 active super representatives have produced a block at or above its height. |
| Soroban and Stellar RPC | Stellar | Soroban is the smart contract platform on the Stellar network; its data is served by Stellar RPC rather than by Horizon. |
| State root | EVM chains | The state root is the root hash of the global state after applying the changes in a block, stored in the block header. |
| Stroop (Stellar) | Stellar | A stroop is the smallest unit of a Stellar asset, one ten-millionth of it. |
| Super representative (TRON) | Tron | A super representative (SR) is one of TRON's 27 active block producers, elected through delegated proof of stake by stakers' votes. |
| Transaction receipt | EVM chains | A transaction receipt is the record of what happened when an EVM transaction was included: its status, gas used, logs and, for deployments, the new contract address. |
| Transaction trace | EVM chains | A transaction trace is a replay of an EVM transaction's execution that reports what happened inside it — for example every call frame, with its type, sender, recipient and value. |
| TRC-20 | Tron | TRC-20 is TRON's standard for fungible token contracts, parallel to Ethereum's ERC-20. |
| TRON address formats (hex 41 and Base58) | Tron | A TRON address is 21 bytes — the byte 0x41 followed by 20 bytes — written either as 42 hex characters starting with 41 or as 34 Base58Check characters starting with T. |
| WebSocket subscription | EVM chains, Solana | A WebSocket subscription asks an RPC node to push notifications for new events — blocks, logs, account changes — over an open WebSocket connection. |
| Wei and gwei | EVM chains | Wei is the smallest denomination of ether, 10⁻¹⁸ ETH; gwei (giga-wei) is 10⁻⁹ ETH. |
| Workchain (TON) | TON | A workchain is a TON blockchain with its own rules and account space. |
How to use this section
- Find the term in the table; the definition column answers the question on its own.
- Open the term for the longer explanation, the RPC methods it affects and its public sources.
- If a call returns an empty or unexpected result rather than an error, the Learn pages explain the symptom.
FAQ
- What does this glossary cover?
- Terms you meet when reading or sending blockchain data over RPC on Solana, EVM chains (Ethereum, BNB Smart Chain, Polygon, Base), TON, Tron and Stellar — definitions that hold on any node and any provider.
- Where do the definitions come from?
- Each term lists its public sources: protocol documentation, specifications and EIPs such as the Solana RPC docs, ethereum.org, EIP-155 and the JSON-RPC 2.0 specification.