I am an amateur in this subject and out of interest compiled these notes from references to which I have access. Therefore I am sure that there may be many inaccuracies lurking in them. Reader beware! Corrections would be appreciated.
The sacrament of Confirmation confirms and perfects the vow of faithfulness to Christ and his Gospel made by or on behalf of a recipient at his/her baptism, and confers on the recipient the gift of the Holy Spirit.
The Roman Catholic Church believes that the sacrament of Confirmation should be received after the person has reached the age of reason, having sufficient maturity to receive the Holy Spirit, which, according to Acts 8:14-17, is not conferred at Baptism. It also provides an opportunity for the bishop of a church community to become personally acquainted with the new members of his flock when they reach the age of reason.
Following the renewal of baptismal promises and the profession of faith by the confirmands, the bishop prays that the confirmands may be blessed with the gift of the Holy Spirit as described in Acts 8:14-17 and anoints them with the chrism (scented ointment), and lays his hands on them as described in Acts 8:14-17. In the Eastern Orthodox Church the Sacraments of Initiation, namely Baptism, Confirmation, and First Communion are usually celebrated together.
Acts 8:14-17Douay-Rheims 1899 American Edition (DRA)
14 Now when the apostles, who were in Jerusalem, had heard that
Samaria had received the word of God, they sent unto them Peter and
John. 15 Who, when they were come, prayed for them, that they might
receive the Holy Ghost. 16 For he was not as yet come upon any of
them; but they were only baptized in the name of the Lord Jesus.
17 Then they laid their hands upon them, and they received the Holy
Traditionally a Catholic should have received the sacraments of Baptism and Confirmation (and Confession) before being allowed to receive First Communion, though relaxation of this order was subsequently authorised.
A clear overview of Confirmation is given in
The Catechism of the Catholic Church gives a detailed description of the Catholic sacrament of Confirmation. Since the Catholic Church considers the sacrament of Eucharist to be essential for the Catholic Christian, and requires that it be received at least once a year, and given that the Catholic Christian is required to have received Baptism and Confirmation before receiving First Communion, it may be deduced that a Catholic Christian is required to be have received Confirmation in order to continue practicing his faith.
Regarding the history of the sacrament of Confirmation, the following seems to be a good starting point:
In this it appears that St Ambrose of Milan was one of the first to use the term “Confirmation”. It is likely that before this term entered into usage the term “Chrism” as still used in the Eastern Orthodox Church and in the Catholic Church in some countries. In Italian the "Confirmation" sacrament is known as "Cresima", a word which is obviously derived from the Greek root of the word "Chrism".
St. Ambrose addressing the catechumens who had already been baptized
and anointed, says: "Thou hast received the spiritual seal, the Spirit
of wisdom and of understanding . . . . Keep what thou hast received.
God the Father has sealed thee; Christ the Lord has confirmed thee;
and the Spirit has given the pledge in thy heart, as thou hast learned
from what is read in the Apostle" (On the Mysteries 7.42).