What is "ng-controller"

It is part of the Angular MVC Components. The ngController Directive specifies a class of controller. The class contains the business logic behind the application to decorate the space with functions and values Note that you can also attach the controllers to the DOM by declaring it in a route setting through the $route service. A common error is declaring the controller again using ng-controller in the model itself. This will cause the controller to be connected and run twice.

Taken from Angular’s own website here.