The term chrismation is used because of the chrism (perfumed holy oil, usually containing myrrh (μύρον), and consecrated by a bishop) with which the recipient of the sacrament is anointed, while the priest speaks the words sealing the initiate with the Gifts of the Holy Spirit.
In the Roman Catholic Church and the majority of the Anglican Communion, since the sacrament is ordinarily administered only by a bishop, and thus is usually conferred separately from baptism, the obligation to receive it arises only later. Originally, when adult baptism was more common as the norm, all the catechumens would be baptized and chrismated by the bishop at the baptistry of the diocesan cathedral. Infant baptism at the parish church by the local presbyter became the norm as growth by conversion slowed and growth by reproduction became the norm; the necessity to baptize infants as soon as possible made the direct involvement of the bishop impractical. However, it must be remembered that all Christians are technically considered "converts," as one is baptized, not born, a Christian; it is necessarily a transformative conversion from the natural-born state of man. This is reflected in the fact that the rites of infant baptism retain the symbolism and rites of the catechumenate, even if in a compacted form. However, to retain the connection to the bishop and Apostolic unity, the West still usually maintains the bishop as the minister of chrismation, even though this involves a postponement of confirmation until some time after baptism.
In the Latin-Rite (i.e., Western) Catholic Church, the sacrament is customarily conferred only on persons old enough to understand it, and the ordinary minister is a bishop (see Confirmation). Only for a serious reason may the diocesan bishop delegate a priest to administer the sacrament (canon 884 of the Code of Canon Law). However, a priest may by law confer the sacrament if he baptizes someone who is no longer an infant or admits a person already baptized to full communion, or if the person (adult or child) to be confirmed is in danger of death (canon 883):
"The practice of the Eastern Churches gives greater emphasis to the unity of Christian initiation. That of the Latin Church more clearly expresses the communion of the new Christian with the bishop as guarantor and servant of the unity, catholicity and apostolicity of his Church, and hence the connection with the apostolic origins of Christ's Church" (Catechism of the Catholic Church, §1292).
Reserving administration of the sacrament to a bishop, who cannot be present at every infant baptism, meant that large groups of older children and young adults were confirmed together, making the occasion something of a rite of passage and an opportunity to affirm a personal commitment to the faith. Though traditionally this was also the occasion for the reception of their First Holy Communion, since the early twentieth century, when Pope Pius X encouraged the admission of children to reception of the Eucharist as soon as they reached the age of reason, those being confirmed have often been receiving the Eucharist for several years. First Communion and Confirmation thus became separated in the last century, with Communion coming to be received, untraditionally, before Confirmation. However, the three sacraments of Christian initiation, baptism, confirmation and Eucharist, are increasingly conferred, within the Roman Catholic Church, in the traditional order, which is obligatory when an adult is baptized. More and more diocese are administering confirmation at the age of reason and preparing children to receive their first communion at that same confirmation Mass.
In the Lutheran church, chrismation is usually conferred immediately after baptism, while "Confirmation" has come to describe a rite of a mature acknowledgement of the faith, graced by the laying-on of the bishop's hands.
In both Eastern and Western traditions, chrismation is considered to bind the recipients more perfectly to the Church, and to enrich them with a special strength of the Holy Spirit. Some theologians propose that chrismation conveys the "Baptism of the Holy Spirit," the particular gifts (or charismata) of which may be latent or become manifest over time according to God's will. The Roman Catholic interpretation can be found in the Catechism of the Catholic Church, 1285-1321 Part 2, Section 2, Chapter 1, Article 2