A knife is a tool with a cutting edge or blade, hand-held or otherwise, with most having a handle. Some types of knives are used as utensils, including knives used at the dining table and knives used in the kitchen. Many types of knives are used as tools, such as the combat knife carried by soldiers, the pocket knife carried by hikers and the hunting knife used by hunters. Knives are also used as a traditional or religious implement, such as the kirpan. Some types of knives are used as weapons, such as daggers or switchblades. Some types of knives are used as sports equipment. Knives are also used in agriculture, food harvesting etc.; the sickle, the scythe and even the combine harvester are knives.
Knife-like tools were used at least two-and-a-half million years ago, as evidenced by the Oldowan tools. Originally made of rock, bone, flint, and obsidian, knives have evolved in construction as technology has, with blades being made from bronze, copper, iron, steel, ceramics, and titanium. Many cultures have their unique version of the knife. Due to its role as humankind's first tool, certain cultures have attached spiritual and religious significance to the knife.