This is a time, of no fixed duration or structure, for asking questions about the Catholic faith and an introduction to Gospel values. It is an opportunity for those who are not Catholic who want to explore what it would mean for them to become a Catholic Christian.
FIRST STEP: Acceptance into the Order of Catechumens (Rite of Welcome)
This is a liturgical ceremony or rite marking the beginning of the catechumenate proper, as the candidates express and the Church accepts their intention to respond to God's call to follow the way of Christ as a member of the Catholic church.
This is the time, in duration corresponding to the progress of the individual, for the nurturing and growth of the catechumens' faith and conversion to God; celebrations of the word and prayers of exorcism and blessing are meant to assist the process.
SECOND STEP: Election or Enrollment of Names (Rite of Election)
This is the liturgical ceremony or rite, usually celebrated on the First Sunday of Lent at the Cathedral by the Bishop, by which the Church formally ratifies the catechumens' readiness for the sacraments of initiation and the catechumens, now the elect, express the will to receive these sacraments. At the parish, there is usually a Rite of Sending at the regular Sunday Mass that will have the catechumen (unbaptized person) sign their name in the Book of Life to presented to the Bishop and the candidate (who is already baptized but making a profession of faith in the Catholic church) present their baptismal certificate signifying that they are already listed among those in the Book of Life.
This is the time immediately preceding the elects' initiation, usually the Lenten season preceding the celebration of ther Initiation Sacraments. This is a time of reflection, intensely centered on conversion, marked by celebration of the scrutinies and presentations and of the preparation rites on Holy Saturday.
THIRD STEP: Celebration of the Sacraments of Initiation - Baptism, Confirmation, and Eucharist
This is the liturgical ceremony or rite, usually integrated into the Easter Vigil, by which the elect are initiated through baptism, confirmation, and the Eucharist. Candidates who are making a profession of faith but are already baptized can receive the Sacraments of Initiation at any time; however, those adults who are preparing for baptism usually are received at the Easter Vigil. Candidates who are already baptized will make a profession in faith and then be welcomed to receive the Eucharist.
This is the time, usually the Easter season, following the celebration of initiation, during which the newly initiated experience being fully a part of the Christian community by means of pertinent catechesis and particularly by participation with all the faithful in the Sunday eucharistic celebration.
~Taken from the Rite of Christian Initiation for Adults