Angular.js uses several directives prefixed with
ng stands for "Angular;" all of the built-in directives that ship with Angular use that prefix. Similarly, it is recommended that you do not use the
ng prefix on your own directives in order to avoid possible name collisions in future versions of Angular.
From the FAQ:
Why is this project called "AngularJS"? Why is the namespace called "ng"?
Because HTML has Angular brackets and "ng" sounds like "Angular".