According to the Catechism of the Catholic Church (CCC) paragraph 1069
The word "liturgy" originally meant a "public work" or a "service in the name of/on behalf of the people." In Christian tradition it means the participation of the People of God in "the work of God." Through the liturgy Christ, our redeemer and high priest, continues the work of our redemption in, with, and through his Church.
More information here from CCC: The Celebration of the Christian Mystery
Sacraments of Christian Initiation: Baptism, Confirmation, Eucharist
Sacraments of Healing: Reconciliation and Anointing of the Sick
Sacraments of Service: Matrimony and Holy Orders
The sacraments are efficacious signs of grace, instituted by Christ and entrusted to the Church, by which divine life is dispensed to us” (CCC 1131). They are sacred and visible signs that are instituted by Jesus to give us grace, an undeserved gift from God. (CCC 1084). Christ was present at the inception of all of the sacraments, which He instituted 2,000 years ago. Christ is also present every time each sacrament is celebrated. The sacraments touch all the stages and all important moments of the Christian life (CCC 1210).
The Sacrament of Baptism cleanses us of original sin, which we inherited from Adam and Eve.
This sacrament is primarily called Baptism because of the central rite with which it is celebrated. To baptize means to “immerse” in water. The one who is baptized is immersed into the death of Christ and rises with him as a “new creature” (2 Corinthians 5:17). This sacrament is also called the “bath of regeneration and renewal in the Holy Spirit” (Titus 3:5); and it is called “enlightenment” because the baptized becomes “a son of light” (Ephesians 5:8). - Compendium of CCC 252
CCC Article 1 - 1213-1284
Why we baptize infants/children
Go, therefore, and make disciples of all nations,
baptizing them in the name of the Father, and of the Son, and of the holy Spirit,
teaching them to observe all that I have commanded you.
And behold, I am with you always, until the end of the age.
Matthew 28:19-20
The Sacrament of Confirmation seals the Holy Spirit in you.
It is called Confirmation because it confirms and strengthens baptismal grace. - Compendium of CCC 266
The effect of Confirmation is a special outpouring of the Holy Spirit like that of Pentecost. This outpouring impresses on the soul an indelible character and produces a growth in the grace of Baptism. It roots the recipient more deeply in divine sonship, binds him more firmly to Christ and to the Church and reinvigorates the gifts of the Holy Spirit in his soul. It gives a special strength to witness to the Christian faith. - Compendium of CCC 268
Before you receive the Sacrament of Confirmation, you are encouraged to select a patron saint.
CCC Article 2 - 1285 - 1321
Then they laid hands on them and they received the holy Spirit.
Acts 8:17
The Sacrament of the Holy Eucharist is the Body and Blood of Jesus Christ.
The Eucharist is the very sacrifice of the Body and Blood of the Lord Jesus which he instituted to perpetuate the sacrifice of the cross throughout the ages until his return in glory. Thus he entrusted to his Church this memorial of his death and Resurrection. It is a sign of unity, a bond of charity, a paschal banquet, in which Christ is consumed, the mind is filled with grace, and a pledge of future glory is given to us. - Compendium of CCC 271
Different mass postures and gestures (from USCCB)
Church Liturgical Year and liturgical colors
CCC Article 3 - 1322 - 1419
Whoever eats my flesh and drinks my blood remains in me and I in him..
John 6:56
While they were eating, Jesus took bread, said the blessing, broke it, and giving it to his disciples said, "Take and eat; this is my body." Then he took a cup, gave thanks, and gave it to them, saying, "Drink from it, all of you, for this is my blood of the covenant, which will be shed on behalf of many for the forgiveness of sins.
Matthew 26:26-28
For I received from the Lord what I also handed on to you, that the Lord Jesus, on the night he was handed over, took bread,
and, after he had given thanks, broke it and said, “This is my body that is for you. Do this in remembrance of me.”
In the same way also the cup, after supper, saying, “This cup is the new covenant in my blood. Do this, as often as you drink it, in remembrance of me.”
For as often as you eat this bread and drink the cup, you proclaim the death of the Lord until he comes.
Therefore whoever eats the bread or drinks the cup of the Lord unworthily will have to answer for the body and blood of the Lord.
A person should examine himself, and so eat the bread and drink the cup.
For anyone who eats and drinks without discerning the body, eats and drinks judgment on himself.
1 Corinthians 11:23-29
The Sacrament of Reconciliation cleanses you of your sins.
Since the new life of grace received in Baptism does not abolish the weakness of human nature nor the inclination to sin (that is, concupiscence), Christ instituted this sacrament for the conversion of the baptized who have been separated from him by sin. - Compendium of CCC 297
CCC Chapter 2 Article 4 - 1420 - 1498
(Jesus) said to them again, "Peace be with you. As the Father has sent me, so I send you."
And when he had said this, he breathed on them and said to them, "Receive the holy Spirit.
Whose sins you forgive are forgiven them, and whose sins you retain are retained."
John 20:21-23
The Sacrament of the Anointing of the Sick is for all who face a serious illness or surgery or who are impaired by old age. This involves the forgiveness of all sins of the person receiving the sacrament.
Any member of the faithful can receive this sacrament as soon as he or she begins to be in danger of death because of sickness or old age. The faithful who receive this sacrament can receive it several times if their illness becomes worse or another serious sickness afflicts them. The celebration of this sacrament should, if possible, be preceded by individual confession on the part of the sick person. - Compendium of CCC 316
This sacrament confers a special grace which unites the sick person more intimately to the Passion of Christ for his good and for the good of all the Church. It gives comfort, peace, courage, and even the forgiveness of sins if the sick person is not able to make a confession. Sometimes, if it is the will of God, this sacrament even brings about the restoration of physical health. In any case this Anointing prepares the sick person for the journey to the Father’s House. - Compendium of CCC 319
CCC Chapter 2 Article 5 - 1499 - 1532
Is anyone among you suffering? He should pray. Is anyone in good spirits? He should sing praise.
Is anyone among you sick? He should summon the presbyters of the church, and they should pray over him and anoint (him) with oil in the name of the Lord,
and the prayer of faith will save the sick person, and the Lord will raise him up.
If he has committed any sins, he will be forgiven.
James 5:13-15
The Sacrament of Holy Matrimony is where God unites a man and a woman becoming husband and wife through a sacred covenant with God and each other.
God who is love and who created man and woman for love has called them to love. By creating man and woman he called them to an intimate communion of life and of love in marriage: “So that they are no longer two, but one flesh” (Matthew 19:6). God said to them in blessing “Be fruitful and multiply” (Genesis 1:28). - Compendium of CCC 337
CCC Chapter 2 Article 7 - 1601 - 1666
He said in reply, "Have you not read that from the beginning
the Creator 'made them male and female'
and said, 'For this reason a man shall leave his father and mother
and be joined to his wife, and the two shall become one flesh'?
So they are no longer two, but one flesh.
Therefore, what God has joined together, no human being must separate."
Matthew 19:4-6
It is the sacrament through which the mission entrusted by Christ to his apostles continues to be exercised in the Church until the end of time. - Compendium of CCC 322
Holy Orders is the sacrament through which the mission entrusted by Christ to his apostles continues to be exercised in the Church until the end of time: thus it is the sacrament of apostolic ministry. It includes three degrees: episcopate, presbyterate, and diaconate. - CCC 1536
CCC Chapter 2 Article 6 - 1533 - 1600
Then he took the bread, said the blessing, broke it, and gave it to them, saying, “This is my body, which will be given for you; do this in memory of me.”
Luke 22:19
Brothers, select from among you seven reputable men, filled with the Spirit and wisdom, whom we shall appoint to this task,
whereas we shall devote ourselves to prayer and to the ministry of the word."
The proposal was acceptable to the whole community, so they chose Stephen, a man filled with faith and the holy Spirit, also Philip, Prochorus, Nicanor, Timon, Parmenas, and Nicholas of Antioch, a convert to Judaism.
They presented these men to the apostles who prayed and laid hands on them.
Acts 6:3-6