A latent print is a chance impression left on a surface that has come into contact with friction ridge skin (fingers and palms of the hand and toes and soles of the feet). The latent print is usually "hidden" or not visible to the human eye. Therefore, latent prints have to be processed by some means to render them visible. A latent print is composed mainly of sweat and any foreign material that may be on the finger, palm or foot at the time the print is deposited on a surface.