A knife is a sharpened piece of metal with a pointed end, used for cutting or as a weapon. Knives have been used since prehistoric times and are one of the most common tools in the world. Today, there are many different types of knives, including kitchen knives, pocket knives, and hunting knives. Some knives are designed for specific tasks, such as carving or slicing.Knives are made from a variety of materials, including steel, plastic, and even bone. The blade of a knife can be either straight or serrated. Knives can be sharpened in many ways, including with a honing stone or steel. When using a knife, it is important to exercise caution and avoid cutting yourself.