What is a validation group and how do you create a validation group?

Answer:

This is a group which allows you to combine different validation controls in a single group on a page. With this, each validation group will going to perform its independent validation property as compared to other validation groups present on that page.

You can create a validation group by changing the ValidationGroup property to the same name for all the controls that you want to group. You can define a name to validation group, but you must have to use the same name for all controls of the group.