What are the styling forms that ngModel adds to CSS classes in Angular?

Angular's `ngModel` directive doesn't directly add specific styling forms to CSS classes. However, Angular provides a set of classes that you can use to style form controls based on their validation state and user interaction. These classes are part of the Angular forms module.

Here are some of the common classes applied to form controls by Angular:

1. **ng-valid:** Applied to a form control when its value is valid according to the specified validation rules.

2. **ng-invalid:** Applied to a form control when its value is invalid according to the specified validation rules.

3. **ng-pristine:** Applied to a form control when it has not been touched by the user (pristine state).

4. **ng-dirty:** Applied to a form control when it has been touched by the user (dirty state).

5. **ng-touched:** Applied to a form control when it has been blurred or touched by the user.

6. **ng-untouched:** Applied to a form control when it has not been blurred or touched by the user.

These classes help you apply styles to form controls based on their state, making it easier to give users feedback on the validity of their inputs.

Example usage in CSS or Angular templates:

```css
/* Apply styles to invalid inputs */
input.ng-invalid {
  border: 1px solid red;
}

/* Apply styles to valid inputs */
input.ng-valid {
  border: 1px solid green;
}

/* Apply styles to touched (blurred) inputs */
input.ng-touched {
  outline: none;
}
```

In Angular templates:

```html
<input type="text" [(ngModel)]="myValue" name="myInput" class="form-control" [ngClass]="{'is-invalid': myInput.invalid && (myInput.dirty || myInput.touched)}">
```

In this example, the `ng-invalid` class is applied when the input value is invalid, and the additional styling is applied conditionally using `[ngClass]` based on the control's `dirty` and `touched` states. Adjust the classes and styles based on your specific requirements.