'''Iconostasis''' (also ''icon screen'') is a screen or wall which serves as a stable support for [[icon]]sand marks the boundary between the [[nave]] and the [[altar]] or sanctuary. The term can also refer to a folding, portable set of icons. There has been historically and continues to be a vast range of styles for iconostases: Some are simply two icons of the [[Theotokos]] and the [[Jesus Christ|Lord]]; the most complex, cathedral icon screens have multiple tiers with many icons per tier. The iconostasis is perhaps the most distintive feature of Byzantine rite churches. It evolved from the Byzantine templon, originally a small rail without icons that marked the boundary between the nave and the altar.

A number of guidelines or [[rubric]]s govern which icons are on which parts of the iconostasis, although there is some room for variation. There are also guidelines for who should enter or leave the sanctuary by which door. These guidelines were developed over the course of many centuries, with both theologically symbolic and practical reasons for them. Though icon screens they vary in size, shape and number of icons, there are some general patterns when designing the following is a basic layout of an iconostasisicon screen which one might find in typical parish church.