The roots of confirmation are found in Acts of the Apostles 8:14 – 17, “Now when the apostles in Jerusalem heard that Samaria had accepted the word of God, they sent them Peter and John, who went down and prayed for them, that they might receive the Holy Spirit, for it had not yet fallen upon any of them; they had only been baptized in the name of the Lord Jesus. Then they laid hands on them and they received the Holy Spirit.”
See also the Gospel of Saint John, chapter 14 where Christ speaks of the coming of the Holy Spirit on the Apostles.
In the teaching of the Roman Catholic Church, Confirmation, known also as Chrismation, is one of the seven sacraments instituted by Christ for the conferral of sanctifying grace and the strengthening of the union between individual souls and God.
From this fact, Confirmation brings an increase and deepening of baptismal grace: