Lettuce is a leafy green vegetable that people eat raw in salads or on sandwiches. Its crisp, mild-tasting leaves grow in rounded bunches called heads. You've probably seen iceberg lettuce, which forms tight, pale green heads that crunch when you bite them, or romaine lettuce, with its longer, darker leaves often used in Caesar salads.

Lettuce has been grown for thousands of years, originally by ancient Egyptians and Romans. Today it's one of the most common vegetables worldwide. Because lettuce is mostly water (about 95%), it stays cool and refreshing even on hot days. Farmers grow lettuce in large fields, and grocery stores often mist it with water to keep it fresh and crisp.

The word can also appear in the slang expression lettuce for money, because dollar bills are green like lettuce leaves. This usage is informal and playful: “That new bike costs a lot of lettuce!”

Different varieties offer different textures and flavors. Butterhead lettuce has soft, almost silky leaves. Leaf lettuce grows in loose bunches rather than tight heads. While lettuce doesn't have a strong flavor on its own, its fresh crunch makes it perfect for adding texture to meals.