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

Some terms come up in nearly every explanation of how Solana works, and most explanations assume you already know them. This glossary defines them in one place.

Lamport

The smallest unit of SOL, like wei on Ethereum or the satoshi on Bitcoin. One SOL is exactly 1,000,000,000 (one billion) lamports. The chain does all its accounting in lamports: every account stores its balance as a lamport count, and fees and rent deposits are counted the same way. SOL is the unit people read. A transaction fee of 5,000 lamports is 0.000005 SOL.

SOL

The Solana network's own token. It pays transaction fees, funds rent-exemption deposits and is what you stake with validators. Most apps show balances in SOL and convert from lamports for you.

Rent-exemption

Every Solana account has to hold a minimum amount of SOL, based on how much data it stores, to stay on the network. That minimum is the rent-exemption threshold. You pay it once when the account is created, and after that the account stays with no further charge. The SOL is a deposit and isn't spent. You get all of it back when the account is closed. Rent on Solana explains how it works.

Rent (the old meaning)

Older Solana documentation sometimes uses "rent" for a charge taken every epoch from accounts that weren't rent-exempt. That mechanism has been phased out in practice, because nearly every account today is created rent-exempt. When people say "rent" now, they almost always mean the rent-exemption deposit described above.

Compute unit (CU)

A measure of how much work a transaction does. More instructions, more account reads and writes, and more complex program logic all use more compute units. Every transaction has a compute budget, either the default or one it requests, and a transaction that goes over it fails. Priority fees are priced per compute unit, in micro-lamports. You pay them to make it more likely a validator includes your transaction sooner.

Epoch

A period of roughly a day, about 432,000 slots, that Solana uses for staking and for scheduling validators. Stake activation, deactivation and reward payouts all happen at epoch boundaries. How Solana staking works explains why.

Slot

The basic unit of time in Solana's consensus. Since October 2026 a slot is about 200 milliseconds (it was 400 before), and in each slot one validator is scheduled to produce a block. An epoch is a fixed number of slots, about 432,000. The "current slot" number on a network status page is the count of slots since the chain started.

Associated token account (ATA)

A token account whose address is derived from a wallet address and a token's mint address. It's the standard, predictable place where a wallet's balance of a token lives. Each token a wallet holds gets its own ATA, and each one has its own rent deposit. Understanding Solana PDAs explains how the derivation works.

Mint

The on-chain account that defines a token: its total supply, its decimals and its authorities (mint, freeze, and for older-style tokens a separate metadata update authority). A token account is different. It holds one holder's balance of the mint.

Authority

A key that has one specific permission over an account. A mint authority can create new supply, a freeze authority can lock token accounts and an update authority can change metadata. Authorities can be revoked (set to None) for good. See revoking mint and freeze authority.

If you want to see rent deposits come back to you, Rent Reclaim closes your empty token accounts and returns their SOL. The Solstack docs overview shows how the tools fit together.