"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.'

And likewise, the cup after they had eaten, saying, 'This cup is the new covenant in my blood, which will be shed for you.'" 

Luke 22:19-20

The chief form of worship in the Catholic Church is the Mass. As Catholics, we have an obligation to attend Mass every Sunday, as we observe the Third Commandment, remembering to keep holy the sabbath day. We are also to attend Mass on Holy Days of Obligation.