Definition
Data availability is a consensus-related property of a blockchain or distributed ledger that denotes whether all necessary transaction and state data for a given block or batch is fully published and retrievable by network participants. It concerns the guarantee that sufficient encoded data is accessible to independently verify block validity, reconstruct state, and detect invalid or withheld data, without relying on privileged or centralized data providers.
In Simple Terms
Data availability is the assurance that all the data needed to check and rebuild a blockchain’s blocks is actually posted and reachable on the network. It means participants can obtain the full information behind recorded transactions and states, instead of trusting others to hold or reveal that data for them.
Context and Usage
The term data availability is central in discussions of blockchain security models, scaling architectures, and modular designs that separate execution, consensus, and data layers. It appears in debates about rollups, data availability sampling, and committees, as well as in protocol research on preventing data withholding attacks. It is also a key consideration when evaluating the robustness of cross-chain systems and off-chain computation frameworks.