How Does a Transaction’s Gas Fee Relate to Its Priority in the Mempool?

In most blockchain systems, the gas fee acts as a bid for inclusion in the next block. Transactions with higher gas fees are typically prioritized by miners or validators because they offer greater rewards.

This is the mechanism exploited in front-running: the front-runner pays a higher fee than the victim's pending transaction to ensure their trade is processed first. This priority system is fundamental to the MEV problem.