The seven Sacraments are: Baptism, Penance/Reconciliation, Holy Eucharist, Confirmation, Matrimony, Holy Orders, and Extreme Unction/Anointing of the Sick.
Baptism is given "in the Name of the Father, and of the Son, and of the Holy Spirit." Baptism only given once and is permanent; even if a person later "leaves" the Catholic Church, he/she is still a member, and if the person repents and returns to the Church, no rebaptizing is necessary. If there is uncertainty of a person's baptism of lack thereof, "conditional baptism" is administered ("If you have not already been baptised, I baptise you in the Name...")
All properly baptised persons, even those not in complete communion with the Roman Pontiff, are members of the Church of Christ and may rightfully be called "Christians" and "brethren in Christ." Baptism permanently makes one a Christian, cannot be undone, and never needs to be given a second time. Although a person may enter into heresy or schism, or even completely reject Christianity and apostasize, the person will never be able to cease being a Christian. Although the Catholic Church may use penalties and censures to attempt to reform a person or minimize the harm a person can do, it does not have the power to revoke Baptism or expel a member from the Church.
A penitent is absolved "in the Name of the Father, and of the Son, and of the Holy Spirit." It is required that all mortal sins be confessed, and the confession of venial sins is encouraged. Catholics are required to confess mortal sins at least once a year. There is no limit as to how many times this sacrament may be administered to a penitent.
Bread and wine are transformed into the Body and Blood of Christ in the context of the Sacrifice of the Mass. Communion is usually received in the course of the Mass; however, Communion may also be received in a Communion Service (and even outside of a Communion Service in some cases?) Catholics are required to receive Communion at least once in the course of the Easter period. Catholics must be in the state of grace to receive Communion. Currently, a person may receive communion twice a day, but the second time must be in the course of a complete Mass attended by the recipient.
Confirmation is given once in a person's lifetime and is also permanent. If a person later "leaves" the Catholic Church, and later repents and returns to the Church, no reconfirmation is necessary.
The Sacrament of Matrimony, when properly administered without impediments and consummated, is permanent until the death of one of the two spouses. If a marriage is not properly administered or there are impediments, an annulment is granted, which is a determination that the marriage was never valid in the first place. If a marriage is not consummated, it is possible to get what is called an ecclesiastical divorce. Marriage is only valid between one man and one woman.
Holy Orders is the ordination of candidates to the priesthood. This sacrament is only given once and is permanent; if a priest later "leaves" the Catholic Church, he/she is still a priest, and if the priest repents and returns to the Church, no reordination is necessary. Even if a priest is laicised, he still may give the Last Rites to a person in danger of death. In general, those who are ordained priests are required to be unmarried. An exception is made for certain Protestant ministers who convert to Catholicism.
Extreme Unction/Anointing of the SickEdit
This Sacrament is given in cases of sickness, imminent death, or old age. It is usually given only once per occasion, but in the case of an extended illness, it is often received more than once. When it is administered, it is often given with the Sacraments of Penance and the holy Eucharist; the reception of these sacraments is often collectively called the Last Rites.