The XRP Ledger is a shared, global ledger that is open to all. Individual participants can trust the integrity of the ledger without having to trust any single institution to manage it. The XRP Ledger protocol accomplishes this by managing a ledger database that can only be updated according to very specific rules. Each server in the peer-to-peer network keeps a full copy of the ledger database, and the network distributes candidate transactions, which are applied in blocks according to the consensus process.
The shared global ledger consists of a series of blocks, called ledger versions or simply ledgers. Every ledger version has a Ledger Index which identifies the correct order of ledgers. Each permanent, closed ledger also has a unique, identifying hash value.
At any given time, each XRP Ledger server has an in-progress open ledger, a number of pending closed ledgers, and a history of validated ledgers that are immutable.
A single ledger version consists of several parts:
- A header - The Ledger Index, hashes of its other contents, and other metadata.
- A transaction tree - The transactions that were applied to the previous ledger to make this one.
- A state tree - All the data in the ledger, as ledger entries: balances, settings, and so on.