The Catholic Church is the Church founded by Jesus Christ.  Today,  Catholicism (from Greek "katholikismos, "universal doctrine") is a term which in its broadest sense refers to the beliefs and practices of all Christian churches that perceive themselves to be members of the Body of Christ.  
The Western/Roman branch and three main branches of the Eastern Church (i.e. Eastern Orthodox Church, Oriental Orthodox Church and Church of the East) consider themselves to be the “one, holy, catholic, and apostolic church” in accordance with the Nicene Creed,  and each of them maintains that their denomination is identical with the original Catholic (i.e. universal) church.  Several mainline Protestant churches which continue to accept the Nicene Creed maintain that their denominations are descended from and  remain linked to the universal church.