An icon is a religious work of art, most commonly a painting, in the cultures of the Eastern Orthodox, Oriental Orthodox, and Catholic churches. They are not simply artworks; "an icon is a sacred image used in religious devotion". The most common subjects include Jesus, Mary, saints, and angels. Although especially associated with portrait-style images concentrating on one or two main figures, the term also covers most of the religious images in a variety of artistic media produced by Eastern Christianity, including narrative scenes, usually from the Bible or the lives of saints.

Tempera, also known as egg tempera, is a permanent, fast-drying painting medium consisting of pigments mixed with a water-soluble binder medium, usually glutinous material such as egg yolk. Tempera also refers to the paintings done in this medium. Tempera paintings are very long-lasting, and examples from the first century AD still exist. Egg tempera was a primary method of painting until after 1500 when it was superseded by oil painting. A paint consisting of pigment and binder commonly used in the United States as poster paint is also often referred to as "tempera paint", although the binders in this paint are different from traditional tempera paint.