A reredos is a large altarpiece, a screen, or decoration placed behind the altar in a church. It often includes religious images.
Reredos depicting the Immaculate Conception. Portuguese, 17th century. Santarém, Portugal
New College, Oxford Chapel reredos, UK
Altar of The Basilica of Our Lady of the Pillar in Zaragoza
Iglesia de Nuestra Señora de la Asunción, Tarancón.
An altarpiece is an work of art in painting, sculpture or relief representing a religious subject made for placing at the back of or behind the altar of a Christian church. Though most commonly used for a single work of art such as a painting or sculpture, or a set of them, the word can also be used of the whole ensemble behind an altar, otherwise known as a reredos, including what is often an elaborate frame for the central image or images. Altarpieces were one of the most important products of Christian art especially from the late Middle Ages to the era of Baroque painting.
The Ghent Altarpiece (1432) by Hubert and Jan van Eyck, with its wings open. Considered one of the masterpieces of Early Netherlandish painting, a complex polyptych panel winged altarpiece, which lost its elaborate framework in the Reformation.
Ghent Altarpiece (1432), as above, closed view with the wings folded in.
Vigoroso da Siena's altarpiece from 1291, an example of an early painted panel altarpiece, with the individual parts framed by gables and sculptured elements
Rothenburg: The Altarpiece of the Holy Blood, by Tilman Riemenschneider (1501–1505). An example of an altarpiece with a central, sculpted section and relief wings.