The Rite of Christian Initiation of Adults (often abbreviated RCIA) is the process through which interested adults and older children are gradually introduced to the Roman Catholic faith and way of life.
The RCIA is a communal process and involves a number of stages punctuated by liturgical rites to aid and assist the potential convert toward the final rite, usually at the Easter Vigil at which time they will become full members of the Roman Catholic Church. The entire process takes several months, (ideally a minimum of one complete liturgical year), but participants are generally invited to proceed at a pace which suits them individually. The Church prefers to call this the process and not a program.
A catechumenis a person who has never received baptism. A candidate is a person who was already baptized. The Catholic Church acknowledges other Christian baptisms as long as the Trinitarian formula “in the name of the Father, and of the Son, and of the Holy Spirit” and flowing water was used.