Blob Transaction

A blob transaction is an Ethereum transaction type introduced by EIP-4844 in the Dencun upgrade of March 2024 that carries a large chunk of data, called a blob, alongside the ordinary payload. Blobs are not readable by smart contracts and are deliberately deleted by nodes after a short retention window, so the chain only guarantees the data was available long enough for anyone to check it. Rollups use blobs to post their batched transaction data far more cheaply than storing it as permanent calldata. Blob space is priced by its own fee market, which means blob costs can spike independently of ordinary gas when many rollups compete for the same slots.