What is Proof of Access (PoA) (Arweave)?

Proof of Acccess (PoA) is the consensus mechanism of the Arweave Protocol. In order to mine or verify a new block, miners must provide cryptographic proof that they have access to a recall block, which is a block from earlier in the blockweave's history. For this reason, Arweave's consensus algorithm is called Proof of Access, and is a variation of a Proof-of-Work (PoW) algorithm. PoA is intended to incentivize long-term data storage because miners must access older, random blocks from the blockweave's history in order to mine new blocks and receive mining rewards.