Coloured scanning electron micrograph (SEM) of a sweat pore on a human hand. Sweat is released through holes like this onto the surface of the skin from glands below the surface.
The sweat evaporates and this cools the body by carrying away heat. The surrounding area shows the dead cells making up the surface layer of the skin, the stratum corneum.
The oily exudate from these pores, left behind on a surface, is what we see as finger prints. Science Photo Library