The Baptism of adults
The catechumenate, or formation of catechumens, aims at bringing their conversion and faith to maturity, in response to the divine initiative and in union with an ecclesial community. The catechumenate is to be "a formation in the whole Christian life . . . During which the disciples will be joined to Christ their teacher. The catechumens should be properly initiated into the mystery of salvation and the practice of the evangelical virtues, and they should be introduced into the life of faith, liturgy, and charity of the People of God by successive sacred rites."
Source: Catechism of the Catholic Church (Vatican.va)