A match is a tool for making fire under controlled circumstances. Most often, it is a small piece of wood, or hardened paper. At one end, the match is coated with a material that will ignite from friction. The lighting end of a match is known as the match "head". It either contains phosphorus or phosphorus sesquisulfide as the active ingredient and gelatin as a binder. Matches are sold in multiples, packaged together either in a box, or in matchbooks. There are two main types of matches: safety matches, which can be struck only against a specially prepared surface; and strike-anywhere matches, for which any suitably frictional surface can be used.