Sacraments are "efficacious signs of grace, instituted by Christ and entrusted to the Church, by which divine life is dispensed to us." (CCC 1131). 
Sacraments: 

• Give us an increase of God's grace. 
• Are necessary for our spiritual lives and our salvation. 
• Founded by Christ and handed on by the Church. 

"Christ instituted the sacraments of the new law. There are seven: Baptism, Confirmation (or Chrismation), 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."

-Catechism of the Catholic Church (CCC) 1210