In a Nutshell

High-level System Overview

1. State is stored as call data in Solana's ledger, resulting in no rent cost

2. Transaction Specify State: Transactions define the state they access (read/write) and include it in the transaction payload

3. State Validation:

   1. Solana Programs invoke the Light Protocol System Program to update compressed state

      1. The protocol validates the state (validity of read state, sum checks, ownership checks)

      2. The protocol enforces a schema: Classic Accounts → Compressed Accounts. Compressed accounts have a layout similar to classic accounts

4. State Updates: At the end of a transaction, the new state is recorded as a log on the ledger

5. Photon RPC Nodes: These nodes index and persist the logs, making the compressed account state available to clients via the ZK Compression RPC API

6. Forester nodes (cranks): Interact with the Account Compression Program to empty queues, and roll-over trees, where compressed state is stored.