The Role of the Proposer

The proposer’s role is to receive and verify transactions. They execute smart contract code, verify signatures and check if the transaction is within the gas limit. Besides that, they decide what transaction should become part of the block. They also decide in what order transactions are executed in a block.

Another role is to add attestations as described in the section Attesting Blocks and Committees.

After the proposer has built the block, he publishes it to the network so that attestors can see this block.

The transaction ordering and deciding what transaction should go into a block or not gives the proposers a significant influence. They could censor transactions.

For that reason, Ethereum 2.0 introduced proposer builder separation. In short, the entity that proposes the block doesn’t decide on the transactions and transaction ordering in this block.

Proposers are assigned to slots one epoch ahead.