A sacrament is an outward efficacious sign instituted by Christ to give grace. Jesus Christ himself is the sacrament, as he gave his life to save mankind. His humanity is the outward sign or the instrument of his Divinity. It is through his humanity that the life of the Trinity comes to us as grace through the sacraments. It is Jesus Christ alone who mediates the sacraments to allow grace to flow to mankind.
The Catholic Church celebrates seven sacraments which were instituted by Christ during his earthly ministry: