Understanding Accounts

The Account Model Deep Dive

Every piece of data on Solana lives in an account. This is fundamentally different from Ethereum where contracts store their own state.

Account Types

Account Layout

pub struct AccountInfo<'a> {
    pub key: &'a Pubkey,          // 32 bytes - account address
    pub lamports: &'a mut u64,     // 8 bytes  - SOL balance
    pub data: &'a mut [u8],        // variable - stored data
    pub owner: &'a Pubkey,         // 32 bytes - program owner
    pub rent_epoch: u64,           // 8 bytes  - rent tracking
    pub is_signer: bool,           // 1 byte   - signed this tx?
    pub is_writable: bool,         // 1 byte   - writable in tx?
    pub executable: bool,          // 1 byte   - is a program?
}

Rent

Accounts must maintain a minimum balance to stay alive — this is called rent exemption. The minimum is approximately:

rent = 0.00089088 SOL per byte per year

For a typical account with 100 bytes of data, you need about 0.00144768 SOL to be rent-exempt.

Most modern Solana programs require accounts to be rent-exempt at creation time.