How Rollups Work

A rollup is not a separate blockchain in the traditional sense. It is an execution environment that processes transactions off Ethereum, then periodically commits a summary of that activity back to Layer 1.

The L2 state — balances, contract storage, NFT ownership — lives off-chain in the rollup's execution layer. What lands on Ethereum is the minimum needed to reconstruct that state: transaction data, state roots, and either a fraud proof or validity proof depending on the rollup type.

If the sequencer disappears, users can still recover their funds by submitting transactions directly to the L1 rollup contract using the published data. That escape hatch is what makes rollups "secure L2s" rather than trusted intermediaries.