What Is the Concept of “Data Availability” in the Context of L2 Solutions?

Data availability is the guarantee that the data required to reconstruct the state of an L2 chain (like a rollup) has been published to the main L1 chain. This is critical for security because, without the transaction data, a fraud proof cannot be executed, and users cannot exit the L2 in case of a malicious validator.

L2s must ensure the data is available to all participants to prevent censorship and maintain trustless operation.