A church is technically a term for a gathering of citizens in a town (origins from ancient Greek), but is commonly understood by the Christian adoption of the word as gathering of Christians in a building or structure to facilitate worship and the meeting of its members, specifically in Christianity. Originally, Jewish Christians met in synagogues, such as the Cenacle, and in one another's homes, known as house churches. As Christianity grew and became more accepted by governments, notably with the Edict of Milan, rooms and, eventually, entire buildings were set aside for the explicit purpose of Christian worship, such as the Church of the Holy Sepulcher.

Traditional church buildings are often in the shape of a cross and frequently have a tower or dome. More modern church buildings have a variety of architectural styles and layouts; many buildings that were designed for other purposes have now been converted for church use; and, similarly, many original church buildings have been put to other uses.