Oil paint was invented somewhere in the Netherlands by Jan van Eyck. Jan van Eyck is credited with this invention because he was the one that decided to use linseed oil as a base for the paint instead of water or something else. Other methods of painting around that time involved limited colors and quick drying times. Tempura, for example, is a paint made with egg yolks. So it always has a yellowish tint to it.
Up until this time, they hadn’t been able to find an oil that would hold the paint well. Nothing worked to keep the colors vibrant and it didn’t really do the job. Linseed oil takes a long time to dry, so this invention allowed artists to mix colors on the painting, and fix mistakes if they found one.