Paint of any sort is made by combining pigment, which is the source of colour, with medium, which binds the particles of pigment together.
In its wider sense, tempera can mean any one of several paint media, but it now commonly refers to egg tempera alone, that is, paint made using egg yolk as a medium.
Egg tempera has been used since Antiquity. Most early Italian paintings are in this medium. It was often combined with oil painting in late 15th-century Italy, but became less common after 1500.