You've got several dynamics going on here at the same time.

- the "First Name" field demonstrates how through the use of "data-binding" you can bind a value to a form element and refer to it elsewhere on the same page. As you enter the name in the field, you'll see it appear below...

First Name:

You entered {{ firstname }}!

- the checkbox can be used as a toggle switch to change the visibility of a DOM element (click on the checkbox).

Yo, dog!

- using radio buttons, you can display different blocks of text, which can be nice...

Pick a topic...

Dogs Tutorials Cars

The ng-switch directive hides and shows HTML sections depending on the value of the radio buttons...

- you can also bind select boxes tog your application using the ng-model directive. It's the same kind of dynamic as with your radio buttons

Select a topic: Dogs Tutorials Cars

The ng-switch directive hides and shows HTML sections depending on the value of the (now) SELECT...