The Nicene Creed (Greek: Σύμβολον τῆς Νίκαιας, Latin: Symbolum Nicaenum) is the profession of faith or creed that is most widely used in Christian liturgy. It forms the mainstream definition of Christianity for most Christians.
It is called Nicene // because, in its original form (not the form used today), it was adopted in the city of Nicaea (present day Iznik in Turkey) by the first ecumenical council, which met there in the year 325.
The Nicene Creed has been normative for the Catholic Church, the Eastern Orthodox Church, the Church of the East, the Oriental Orthodox churches, the Anglican Communion, and Protestant denominations. It forms the mainstream definition of Christianity itself in Nicene Christianity.
The Apostles’ Creed (in its present form later than either form of the Nicene Creed, but in its original form earlier than them) is also broadly accepted in the West, but is not used in the Eastern liturgy. One or other of these two creeds is recited in the Roman Rite Mass directly after the homily on all Sundays and solemnities (Tridentine feasts of the first class). In the Roman Catholic Church, the Nicene Creed is part of the profession of faith required of those undertaking important functions within the Church.
In the Byzantine Rite the Nicene Creed is always sung or recited at the Divine Liturgy immediately preceding the Anaphora (Eucharistic Prayer) and is also recited daily at compline, as well as at sundry other services.
For English translations of the Nicene Creed in current use, see English versions of the Nicene Creed.