State trie

The state trie is a Merkle-Patricia tree that encodes the full account and contract state of an EVM chain, whose root hash is committed in every block header.

Each block header carries a state root that cryptographically commits to the entire account set — balances, nonces and contract storage — at that height. Full nodes keep enough of the trie to serve current state, but reconstructing balances at an old block requires the historical trie, which only an archive node retains. That is why point-in-time balance and storage queries need archive access. Our archive RPC keeps the full trie history for supported chains, so eth_getBalance at any past block resolves correctly.