The Catechism of the Catholic Church states: "The sacraments are perceptible signs (words and actions) accessible to our human nature. By the action of Christ and the power of the Holy Spirit they make present efficaciously the grace that they signify." (CCC 1084)
"There are seven: Baptism, Confirmation, the Eucharist, Penance, the Anointing of the sick, Holy Orders, and Matrimony. The seven sacraments touch all the stages and all the important moments of Christian life: they give birth and increase, healing and mission to the Christian's life of faith. There is thus a certain resemblance between the stages of natural life and the stages of the spiritual life." (CCC 1210)
The Sacraments are Outward Signs of Grace
Since each sacrament is a perceivable sign of God's grace, one can better understand each sacrament through identifying the sign and the grace received.
Sacraments of Initiation lay the foundations of every Christian life: Baptism is the basis of the whole Christian life, the gateway to life in the Spirit, and the door which gives access to the other sacraments. (CCC 1213) Sign: Water is poured over the candidates head and the words of Baptism are spoken: "I baptize you in the name of the Father, and of the Son, and of the Holy Spirit." Grace: The candidate is cleansed of all sins, including original sin. Baptism gives the initial deposit of Sanctifying Grace to the soul and that it marks the soul forever as a "child of God" never to be removed or repeated.
Holy Eucharist Sign: Bread and wine are transformed into the Body, Blood, Soul, and Divinity of Christ when the priest speaks the words of Consecration: "This is my body. This is my Blood." Grace: The effects of receiving Holy Eucharist are immeasurable, but include profound unity with Christ and the Church, an increase of grace to do good an avoid evil
Confirmation Sign: Chrism(blessed oil), laying on of the hands, the words spoken by the Bishop: "Be sealed with the gift of the Holy Spirit." Grace: The candidate receives an increase of the gifts of the Holy Spirit, a deepening of baptismal grace, a more firm unity to Christ, and the strength of the Holy Spirit to spread and defend the Gospel. Through Confirmation, the confirmed receives an indelible mark on his soul which can never be removed or repeated.
Sacraments of Healing restore health to the body and the soul:
Reconciliation Sign: After the penitent confesses his sins, the priest makes the sign of the cross as he says the words of absolution: "I absolve you from your sins in the Name of the Father, and of the Son, and of the Holy Spirit." Grace: Forgiveness of sins, the grace to resist future temptations
Anointing of the Sick Sign: The priest lays his hands over the sick, prays over them, and anoints them with oil. Grace: The Holy Spirit strengthens the sick with spiritual and sometimes physical aid
Sacraments at the Service of Communion and the Mission of the Faithful are directed towards the salvation of others directly and one's personal salvation as a consequence:
Marriage Sign: A man and woman in full freedom come forth to make their vows before God expressing their commitment to each other Grace: This grace proper to the sacrament of Matrimony is intended to perfect the couple's love and to strengthen their indissoluble unity. By this grace they "help one another to attain holiness in their married life and in welcoming and educating their children." CCC 1641
Holy Orders Sign: The signs of Holy Orders are oil and the laying- on-of-hands. The oil signifies that the one anointed has been called by God to a special service. The laying-on-of- hands signifies that the Church authorizes the anointed to perform this service. Grace: "The grace of the Holy Spirit proper to this sacrament is configuration to Christ as Priest, Teacher, and Pastor, of whom the ordained is made a minister." CCC 1858 "As in the case of Baptism and Confirmation this share in Christ's office is granted once for all. The sacrament of Holy Orders, like the other two, confers an indelible spiritual character and cannot be repeated or conferred temporarily." CCC 1852