Glossary
Layer 2
Also called: L2
A network that processes transactions itself and periodically posts the results to a layer 1, inheriting that chain's security while costing far less to use. Base and Arbitrum are examples.
The practical catch is exit time. Withdrawing from an optimistic rollup back to Ethereum through the official bridge takes about seven days, because the design allows a window in which an incorrect batch can be challenged.
See also
Layer 1A base network that settles its own transactions — Bitcoin, Ethereum, Solana, Tron. Contrast with a layer 2, which relies on a layer 1 underneath it.
RollupA layer 2 that compresses many transactions into one batch posted to the layer 1. Optimistic rollups assume batches are valid unless challenged; zero-knowledge rollups prove validity mathematically.
BridgeA service that lets value move between two networks, usually by locking an asset on one side and issuing a representation on the other. Bridges hold funds while they operate, which has made them a repeated target.
Last checked 19 Oct 2026.