Oil painting is the process of painting with pigments that bound with medium of drying oil — especially in early modern Europe, linseed oil. Often an oil, such as linseed was boiled with a resin such as pine resin or even frankincense, these were called 'varnishes' and were prized for their body and gloss. Other oils occasionally used include poppyseed oil, walnut oil, and safflower oil. These oils give various properties to the oil paint, such as less yellowing or different drying times. Certain differences are also visible in the sheen of the paints depending on the oil. Painters often use different oils in the same painting depending on specific pigments and effects desired. The paints themselves also develop a particular feel depending on the media.

History:
Oil paint was probably developed for decorative or functional purposes in the High Middle Ages. Surfaces like shields — both those used in tournaments and those hung as decorations — were more durable when painted in oil-based media than when painted in the traditional tempera paints.
Most Renaissance sources, in particular Vasari, credited northern European painters of the 15th century, and Jan van Eyck in particular, with the "invention" of painting with oil media on wood panel, however Theophilus (roger of Helmerhausen) clearly gives instructions for oil-based painting in his treatise, On Divers Arts, written in 1125. Early Netherlandish painting in the 15th century was however the first to make oil the usual painting medium, followed by the rest of Northern Europe, and only then Italy. The popularity of oil spread through Italy from the North, starting in Venice in the late 15th century. By 1540 the previous method for painting on panel, tempera had become all but extinct, although Italians continued to use fresco for wall paintings, which was more difficult in Northern climates.