Icons are a specific type of fine art that date back to the Byzantine Empire. These works of devotion are as rich in history as they are in symbolism, incorporating Greek, Roman, and Middle Eastern influences. Typically, they are a one-dimensional portrait of a holy person. They are believed to physically bring the viewer closer to the subject of the art as the holy person manifests in their presence.
Icons begin in prayer and are specifically intended to promote prayer. Countless requests are believed to be answered when praying before them. And reproductions are as valued as originals.
You can read more about icons in Grieving with Mary. Finding Comfort and Healing in Devotion to the Mother of God.