The Sacraments of the Catholic Church are, the Church teaches, "efficacious signs of grace, instituted by Christ and entrusted to the Church, by which divine life is dispensed to us. The visible rites by which the sacraments are celebrated signify and make present the graces proper to each sacrament. They bear fruit in those who receive them with the required dispositions."
Though not every individual has to receive every sacrament, the Church affirms that, for believers as a whole, the sacraments are necessary for salvation, as the modes of grace divinely instituted by Christ Himself. Through each of them Christ bestows that sacrament's particular grace, such as incorporation into Christ and the Church, forgiveness of sins, or consecration for a particular service.
Exerpt from Wikipedia.com