This technique cooks food at a relatively high temperature—212 degrees is the boiling point for water at sea level. When liquids boil, bubbles break through and pop on the surface while the whole batch of liquid churns vigorously. Bubbles are caused by water vapor, a gas, rushing to the surface.

What boiling does. In the case of pasta, churning, boiling water keeps the food in motion, prevents sticking, and cooks quickly so the pasta doesn't get soggy. Green vegetables are tossed into boiling water to cook as quickly as possible so they retain their flavor and bright color in a process called blanching; if they were to simmer gently in a covered pot, their color would dull, and they would lose much of their texture. Boiling causes speedy evaporation, a useful effect for reducing sauces, where the volume of the liquid decreases and flavors are concentrated.

Boiling liquid. When ingredients are boiled, they are done so in water, sometimes containing salt and oil or butter for flavor and texture. The food is usually added to the liquid once it reaches a boil.

Best bets for boiling. This intense cooking method is well suited for pasta, some grains, and green vegetables. Boiling is also useful for reducing sauces.