Tempera is a bright, fast-drying type of paint. Paintings done in tempera are extremely long-lasting—some as old as the first century CE have been found.
Traditionally, tempera paints were mixed with egg yolk, which is why this type of paint is commonly called egg tempera. Egg is still used today, as well as other materials with similar consistencies. Serious painters almost always used tempera before oil paints became popular around 1500. While colors are vivid and long-lasting, a weakness of egg tempera is that it cracks easily and works best when it's applied to wood. The Latin root is temperare, "to mix colors."