Icons have been used in Christianity for almost 2000 years as a way to teach biblical stories and religious teachings through visual representations for illiterate followers. They first became popular in private homes and then churches in the 4th-5th centuries. Some religious traditionalists opposed icons and destroyed them, in a period known as iconoclasm. Today, icons are still painted according to traditional styles and rules, depicting figures like Christ, saints and Mary, and can be found in museums and private collections.