Baptism
  Baptism was instituted to confer upon us the beginnings of the spiritual Life, to transfer us from the state of enemies of God to the state of adoption as sons and daughters of God.

Confirmation
  1) An increase of sanctifying grace making the recipient a "Perfect Christian";
  2) a special sacramental grace consisting in the seven gifts of the Holy Ghost and notably in the strength and courage to confess boldly the name of Christ;
  3) an indelible character by reason of which the sacrament cannot be received again by the same person.

Penance/Confession
  The manner in which we reconcile ourselves with God after we commit the heinous act of sin and, having a contrite heart, truly desire to be reunited fully with God.

Holy Communion
  The Greatest Sacrament, the Holy Eucharist—the Body and Blood, Soul and Divinity, of Jesus Christ—was given to us by Christ so that we may enter into union with Christ Himself and His Love, as when Jesus says "He that eateth my flesh, and drinketh blood, abideth in me, and I in him" (John, 6:57) The Eucharist removes our venial sins from our soul, and is a great aid in avoiding the temptation to commit mortal sins. It is because of this that many Saints have said that the Holy Sacrifice of the Mass (particularly the Eucharist) is "the perfect prayer".

Matrimony
  Contrary to popular misconception, the priest does NOT confer the sacrament of Holy Matrimony—the priest is merely the ‘witness’ to the man and woman making their vows before God. It is the husband and wife who ‘minister’ the Sacrament to themselves from God. However, the fact that a husband and wife make the sacrament between themselves and God does not mean that they can ‘unmake’ this union, as it is an agreement until the death of one of the parties.

Holy Orders
  In the Latin Rite, the current discipline is for only non-married Catholics may be ordained priests; however, converts to the Catholic Faith who are married may later become ordained because the Church recognizes their marriage as valid and does not want to deny them the opportunity to serve the Church as a priest if they had previously joined in marriage in another Church before knowing the fullness of the Catholic Faith.

Anointing Of The Sick
  Administered to a person who is dying, it may be given to both Catholics and non-Catholics who truthfully declare (in danger of death) to have a desire to enter into the Catholic Church and profess the Faith that the Catholic Church teaches.

Source: The Catholic Encyclopedia