Kerygma (noun) ke·ryg·ma \kə->rig-mə\
The word kerygma is related to the Greek verb κηρύσσω (kērússō) (pronounced "kay-roos'-so") meaning to cry or proclaim as a herald. It means proclamation, announcement or preaching.
The kerygma is the message of the Gospel; the apostolic proclamation of salvation through Jesus Christ. It is the core and heart of our faith.
If you were to sum up the core message of the Gospel in just a few sentences, what would you say that it is?
As you can see, the kerygma is not complicated. It is not (yet) concerned with the details of morality or magisterium. It is a telling of the story of our salvation in its simplest and most important form. It is not just for Catholics. It is so fundamental, that this core Gospel message crosses all Christian denomination boundaries and barriers.