As the name suggests, the binding agent in oil paint is oil. The main advantage of oil paint, besides the richness of its colors, is that the colors remain well preserved over time.
Oil paints are also valued by artists for practical reasons as the paint dries more slowly than Tempera paints. Oil based painting reached its apex in the baroque period with such artists as Paul Rubens.
The term tempera painting originates from the Latin verb temperare and roughly translates as mixing. Pigments first have to be mixed with a binding agent when creating a tempera painting. Before the dawn of oil painting, the main binding agents of choice were egg and casein.
Tempera painting was made obsolete by oil painting during the 15th century. Jan van Eyk (1390-1441) was the first to begin using oil paints alongside tempera.