Papal infallibility is a doctrine of the Roman Catholic Church that asserts the Pope is incapable of error when proclaiming definitive teachings on faith and morals. This infallibility applies only when the Pope speaks ex cathedra, or "from the chair," in his official capacity as the leader of the Church. This concept was formally defined during the First Vatican Council in 1870. It does not mean that the Pope is free from personal sin or error in other matters, but rather that certain teachings, when declared under specific conditions, are considered free from error and must be accepted by all Catholics.