How Does a Validator Choose Which Transactions to Include in a Block?

A validator chooses transactions from the mempool based on a strategy that maximizes their profit, subject to the block's gas limit. Under EIP-1559, they prioritize transactions that offer the highest priority fee (tip) and may also consider the total transaction value if they are involved in MEV extraction.

In the Proof-of-Stake system with Proposer-Builder Separation (PBS), the validator's choice is often simplified to selecting the most profitable block header submitted by a block builder.