A knife is any cutting edge or blade, handheld or otherwise, with or without a handle. Knives were used at least two-and-a-half million years ago, as evidenced by the Oldowan tools.
Originally made of rock, flint, and obsidian; knives have evolved in construction as technology has with blades being made from bronze, copper, iron, steel, ceramics, and titanium. Every culture has a unique version of the knife. A knife may be either a fixed-blade or a folding version with blade patterns and styles as varied as their makers and countries of origin. Due to its role as mankind's first tool, certain cultures have attached spiritual and religious significance to the knife.
A knife is any cutting edge or blade, handheld or otherwise, with or without a handle. Knives were used at least two-and-a-half million years ago, as evidenced by the Oldowan tools. 
