The Rites of Christian Initiation of Adults (RCIA) is a series of rituals during Mass and formation sessions where a person prays and learns about becoming Catholic, and how to live out that faith in their daily lives. It is primarily for those who are unbaptized, but also for those who are baptized in a non-Catholic community. It culminates in the celebrations of the Sacraments of Baptism, Confirmation, and the Eucharist.
The first weeks are called Inquiry Sessions, and they allow individuals to ask questions about the Catholic Church and what she professes to be revealed by God as it relates to faith (what to believe) and morals (how to live)
A person does not need to be sure to start the RCIA, but only open to God's will. The RCIA team (those who help lead the formation sessions) will help you to know when you are ready to say yes to God's invitation to you to join His Church. They are kind, welcoming, and hospitable, and are ready to answer your questions.
The Period of the Pre-Catechumenate: A time of asking questions about the Catholic faith and life
The Period of the Catechumenate: A time of spiritual growth beginning with the Rite of Welcoming in which a person prepares to become Catholic
The Period of Enlightenment and Purification: A time beginning with the Rite of Election with the bishop, usually during Lent, where there are Rites at Mass where a person seeks a deeper relationship with Jesus and where there are prayers to cast out any obstalces to that person's relationship.
The Period of Mystagogy: A time beginning with the person's initiation into the Catholic Church through the Sacraments of Baptism, Confirmation, and the Eucharist, where the person "unpacks" all that has happened during the RCIA and sees how God is helping them to continue to grow as a Catholic.