The AngularJS form goes to the following states, starting from the form rendering and when the user has
finished the filling of form.
State 1: pristine and invalid - When the form is first time rendered and the user has not interacted with the form
yet.
State 2: dirty and invalid - User has interacted with the form, but form validity has not been satisfied, yet.
State 3: dirty and valid - User has finished the filling of form and the entire form validations has been satisfied
