How do I close a file that I created using cat > command?

I learning how to use git on a Mac and I'm trying to add a file in one of my branches by using the "cat > " command. The problem I'm having is that I want to end editing the file in the terminal but I do not know how to close it. I'm guessing that I need to change "modes" for lack of a better term. How do I proceed?


Press Control-D.