A knife is a tool with a sharp blade attached to a handle, used for cutting. You use knives every day: to slice bread at breakfast, cut vegetables for dinner, or open packages. A butter knife spreads jam gently, while a chef's knife can chop through a thick carrot with one clean motion.

Knives were among humanity's first tools, invented hundreds of thousands of years ago. Early humans shaped sharp edges from stone, then later from bronze and iron. Today's knives range from tiny pocketknives to long kitchen knives to specialized tools like scalpels that surgeons use in operating rooms.

People also use knife as a verb, meaning to cut with a knife. In cooking, you might knife a ripe tomato or carefully knife around the core of an apple.

Different knives do different jobs. A serrated knife has a jagged edge perfect for sawing through crusty bread. A paring knife is small and precise for peeling fruit. A Swiss Army knife folds up and includes multiple tools. People are taught to use knives safely and skillfully: to hold them carefully, cut away from themselves, and always pay attention to what they are doing.