The practice of keeping the Bread (and occasionally also the Wine) consecrated at the Eucharist, primarily for the purpose of Communion. At first the faithful kept the Bl Sacrament in their homes or on their persons, but from the 4th cent. the churches became the ordinary places for reservation. The Sacrament was kept either in the sacristy or in the church itself, in an aumbry in the wall, in a pyx hanging over the altar, or in a tabernacle on the altar, the last being until recently the normal modern practice in the RC Church, as it still is in the E. Church. Current RC legislation favours reservation in a separate chapel, but allows some latitude. A lamp is kept burning nearby as a sign of honour. Reservation under the Species of Bread only seems originally to have been the common practice in both E. and W., but in the E. the Host is now marked with consecrated Wine from a communion spoon and may then be artificially dried.
In the C of E the 1549 BCP provided for reservation for the Communion of the sick, but the provision was dropped in 1552. In the 19th and 20th cents. the practice was revived in some places. It is implicitly recognized in the rubrics of many modern Anglican liturgies.