Blobs and EIP-4844

Before EIP-4844, rollups posted batch data as regular calldata in Ethereum transactions. Calldata is expensive because every byte is stored permanently in chain history and priced alongside execution gas. Rollup operators passed that cost directly to users.

Blobs are not meant for smart contract storage or permanent records. They exist long enough for the network to verify data availability, then can be pruned. This is proto-danksharding — the first step toward full danksharding, where data is spread across many shards for even lower costs.

For users, the impact was immediate: fees on Arbitrum, Base, Optimism, and other rollups fell dramatically because their largest cost — posting data to L1 — got cheaper overnight.