Explain the Concept of “Sandwich Attacks” as a Specific Type of Front-Running

A sandwich attack is a specific front-running strategy where an attacker places two transactions around a victim's pending trade. The attacker first executes a trade (e.g. a buy) just before the victim's transaction and then executes a second trade (e.g. a sell) immediately after the victim's transaction is confirmed.

The victim's large order moves the market price, which the attacker exploits to buy low and sell high, "sandwiching" the victim's trade for profit. This requires high gas fees to ensure priority.