Lamports, SOL, and Rent: A Glossary for Solana Beginners

A handful of terms show up constantly in any explanation of how Solana works, and most explanations assume you already know them. Here they are, defined precisely, in one place.

Lamport

The smallest unit of SOL — Solana's equivalent of a "wei" (Ethereum) or a "satoshi" (Bitcoin). There are exactly 1,000,000,000 (one billion) lamports per SOL. All on-chain accounting — balances, fees, rent deposits — happens in lamports internally; SOL is the human-friendly display unit built on top. When you see a transaction fee of "5,000 lamports," that's 0.000005 SOL.

SOL

The native token of the Solana network, used to pay transaction fees, fund rent-exemption deposits, and stake to validators. It's also the unit most user interfaces display balances in, converting from the underlying lamport count automatically.

Rent-exemption

Every Solana account must hold a minimum SOL balance, scaled to how much data it stores, to remain on the network permanently — this is the rent-exemption threshold. Pay it once at account creation and the account persists indefinitely with no ongoing charge; the SOL isn't spent, it's a deposit, returned to you in full when the account is closed. Full mechanics in Rent on Solana.

Rent (the historical, now largely irrelevant, meaning)

Older Solana documentation sometimes refers to "rent" as an ongoing per-epoch charge for accounts that weren't rent-exempt — a mechanism that's been effectively phased out in practice, since essentially all accounts today are created rent-exempt from the start. When people say "rent" now, in nearly every practical context, they mean the rent-exemption deposit above, not an ongoing fee.

Compute unit (CU)

A measure of how much computational work a transaction performs — more instructions, more account reads and writes, more complex program logic all consume more compute units. Every transaction has a compute budget (a default, or one explicitly requested), and a transaction that would exceed it fails. Compute units are also what a priority fee is denominated against — a fee in micro-lamports per compute unit, paid to increase the chance a validator prioritizes including your transaction sooner.

Epoch

A fixed period of roughly 2–3 days (about 432,000 slots) that Solana organizes time into for staking and validator-scheduling purposes. Stake activation, deactivation, and reward payouts all happen at epoch boundaries rather than continuously — see how Solana staking actually works for why that specific timing exists.

Slot

The basic unit of time within Solana's consensus — roughly 400 milliseconds, during which one validator is scheduled to produce a block. An epoch is a fixed number of slots (~432,000); the "current slot" number you sometimes see in a network status readout is the running count of these since genesis.

Associated Token Account (ATA)

A token account address deterministically derived from a wallet address plus a token's mint address — the standard, predictable location where a given wallet's balance of a given token lives. Every different token a wallet holds gets its own separate ATA, each independently rent-exempt. See Understanding Solana PDAs for why this derivation works the way it does.

Mint

The on-chain account representing a token itself — its total supply, decimal precision, and authorities (mint, freeze, and for older-style tokens, a separate metadata update authority). Not to be confused with a token account, which represents one specific holder's balance of that mint.

Authority

A keypair granted a specific, narrow permission over an account — a mint authority can create new supply, a freeze authority can lock token accounts, an update authority can change metadata. Authorities can be revoked (set to None) permanently; see revoking mint and freeze authority.

For the mechanics of the concept most directly tied to your wallet balance day to day, Rent Reclaim is a concrete, hands-on way to see rent-exemption deposits actually come back to you. Broader overview of how everything fits together is in the Solstack docs overview.