The altar rail (also known as a communion rail or chancel rail) is a low barrier, sometimes ornate and usually made of stone, wood or metal in some combination, delimiting the chancel or the sanctuary and altar in a church, from the nave and other parts that contain the congregation. Often, a central gate or gap divides the line into two parts. Chancel rails are a very common, but not universal, feature of Roman Catholic, Lutheran, Anglican, and Methodist churches. They are usually about 2 feet 6 inches (76 cm) high, with a padded step at the bottom, and designed so that the wider top of the rail can support the forearms or elbows of a kneeling person.
The altar rail is a modest substitute for earlier barriers demarcating the chancel, the area containing the altar, which was reserved, with greatly varying degrees of strictness, for officiating clergy, including boys as choristers and altar servers. Although it only emerged after the Protestant Reformation, it has been found convenient by both Roman Catholic and more traditional Protestant churches, such as the Lutheran, Anglican and Methodist churches. After the Second Vatican Council, a number of Roman Catholic churches removed their chancel rails, which fell into disuse; on the other hand, Lutheran churches continue to retain many features of medieval church architecture and normatively have chancel rails at which communicants receive the Eucharist.