A snail is a small mollusk with a spiral-shaped shell. Snails are famous for moving very slowly, and for leaving a trail of slime behind them.
If you see snails on a restaurant menu, they're more likely to be listed as escargot, or "edible snail" in French. There are three general categories of snails: land snails, sea snails, and freshwater snails. They all have shells that they can retreat within—without a shell, a similar animal is instead called a slug. Snail can be traced back to the diminutive form of the Old English snaca, "snake" or "creeping thing."