How do you use validation summary?
ASP.NET ValidationSummary Control
This validator is used to display list of all validation errors in the web form. It allows us to summarize the error messages at a single location. We can set DisplayMode property to display error messages as a list, bullet list or single paragraph.
What is validation summary?
The ValidationSummary() extension method displays a summary of all validation errors on a web page as an unordered list element. It can also be used to display custom error messages.