Glossary definition
Slippage
Slippage is the gap between the expected and the executed price of a trade; slippage protection bounds it with a minimum acceptable outcome.
On an automated market maker, the executed price differs from the quoted one: the trade itself moves the pool, and so does every transaction ordered before it. That gap is slippage. Slippage protection lets the caller state the worst outcome it accepts, such as a minimum output amount or a price floor, and the transaction reverts if the market is worse. Without it, a front-run or mispriced transaction executes at whatever price the pool offers.
The protection deserves review of its own. A gate that compares an oracle price to a pool price can be blocked by an attacker who temporarily poisons a shallow pool’s state, so honest deposits fail through the gate.