Angular form validation

form validation using required
<style>
 .my-form {
   -webkit-transition:all linear 0.5s;
   transition:all linear 0.5s;
   background: transparent;
 }
 .my-form.ng-invalid {
   background: red;
 }
</style>
<form name="myForm" ng-controller="FormController" class="my-form">
  userType: <input name="input" ng-model="userType" required>
  <span class="error" ng-show="myForm.input.$error.required">Required!</span><br>
 </form>