All Catholics are Christians, but not all Christians are Catholic. Christianity is the broad religion based on the life and teachings of Jesus Christ. Catholicism is the largest denomination within Christianity, with over 1.3 billion members. Key distinctions of Catholicism include: (1) Apostolic succession — an unbroken chain of bishops from the Apostles. (2) The Pope — the Bishop of Rome and head of the Church. (3) Seven Sacraments — not all Christian denominations recognize all seven. (4) Sacred Tradition — alongside Scripture, the Church's living Tradition is a source of divine revelation. (5) The Eucharist — Catholics believe in the Real Presence of Christ in Communion. (6) Veneration of Mary and saints. (7) Magisterium — the teaching authority of the Church.