A layer 2 is a protocol that provides users the ability to leave an offchain system if its operators go offline and also ensures that the operators of a system cannot cheat. Both of these assumptions need to be provable and enforced onchain.

bitcoin

Are exchanges and ETF's basically another layer two?

crenshaw

https://www.lxresearch.co/starting-to-define-layers-a-year-later/

> A layer 2 is a protocol that provides users the ability to leave an offchain system if its operators go offline and also ensures that the operators of a system cannot cheat. Both of these assumptions need to be provable and enforced onchain.