What Is EIP-1559 and How Did It Change the Gas Fee Mechanism on Ethereum?

EIP-1559 introduced a new transaction fee structure on Ethereum, replacing the simple auction with a system of a mandatory "base fee" and an optional "priority fee" (or tip). The base fee is dynamically adjusted based on network congestion and is burned (removed from circulation), making transaction costs more predictable.

The priority fee goes to the validator as an incentive. This change makes it harder for simple front-running by bidding slightly higher than a competitor.