Data is validated in forms to ensure that the data entered in the form is in the expected format.
The value of a field is validated upon leaving it after entering data by pressing the Tab key or by clicking in a new field. When a field's value is not valid, a red border is displayed around the field. If you click in an invalid field, information about why the value in the field is not valid appears next to the field.
Upon clicking Submit on a form, all the values in all the fields on the form are validated. If any field contains an invalid value, a notification bar appears directly above the form that displays the name of the invalid field or fields and the reason why the value in the field or fields is invalid next to the field name. The form cannot be submitted until the values in the invalid fields are no longer invalid.
You can click on the name of an invalid field in the notification bar to navigate to that field and to display a message explaining the reason why the field is invalid.