The first knives were invented by homo sapiens during prehistoric times and were used as weapons, tools and eating utensils. The Oldowon was used up to 2.5 million years ago and is the oldest known knife-like tool to be discovered as of 2014.
Knives were originally made of flint, rock, bone and obsidian. As of 2014, more modern knives are made from materials such as ceramic, iron, steel, titanium, bronze and copper, and they usually have either a folding or fixed-blade construction. Fixed-blade knives fit inside a sheath, are stronger and do not have moving parts. Folding knives use a pivot that connects the blade to the handle and feature a locking mechanism to prevent accidental opening or injury.