<human>:  When did the first oil painting appear?
<bot>: The first oil painting was made in the early 15th century by a painter named Giotto di Bondone. Giotto was a painter in Florence, Italy, and he created the first true oil painting. The first oil painting was a fresco, a painting on a wall, and Giotto’s work was the first time an artist used oil paint to paint on a flat surface. Oil paint is made of pigments mixed with a liquid medium, which is typically a mixture of linseed oil and turpentine.