Until the Protestant Reformation, a chapel denoted a place of worship that was either at a secondary location that was not the main responsibility of the local parish priest, or that belonged to a person or institution. The earliest Christian places of worship are now often referred to as chapels, as they were not dedicated buildings but rather a dedicated chamber within a building. Most larger churches had one or more secondary altars, which if they occupied a distinct space, would often be called a chapel. In Russian Orthodox tradition, the chapels were built underneath city gates, where most people could visit them. The most famous example is the Iberian Chapel.
Although chapels frequently refer to Christian places of worship, they are also commonly found in Jewish synagogues and do not necessarily connote a specific denomination. In England—where the Church of England is established by law—non-denominational or inter-faith chapels in such institutions may nonetheless be consecrated by the local Anglican bishop. Non-denominational chapels are commonly encountered as part of a non-religious institution such as a hospital, airport, university or prison. Many military installations have chapels for the use of military personnel, normally under the leadership of a military chaplain.
The earliest Christian places of worship were not dedicated buildings but rather a dedicated chamber within a building, such as a room in an individual's home. Here one or two people could pray without being part of a communion/congregation. People who like to use chapels may find it peaceful and relaxing to be away from the stress of life, without other people moving around them.
The word, chapel, like the associated word, chaplain, is ultimately derived from Latin. More specifically, the word "chapel" is derived from a relic of Saint Martin of Tours: traditional stories about Martin relate that while he was still a soldier, he cut his military cloak in half to give part to a beggar in need. The other half he wore over his shoulders as a "small cape" (Latin: capella). The beggar, the stories claim, was Christ in disguise, and Martin experienced a conversion of heart, becoming first a monk, then abbot, then bishop. This cape came into the possession of the Frankish kings, and they kept the relic with them as they did battle. The tent which kept the cape was called the capella and the priests who said daily Mass in the tent were known as the capellani. From these words, via Old French, we get the names "chapel" and "chaplain".
The word also appears in the Irish language in the Middle Ages, as Welsh people came with the Norman and Old English invaders to the island of Ireland. While the traditional Irish word for church was eaglais (derived from ecclesia), a new word, séipéal (from cappella), came into usage.