Introduction A ValidationSummary control is used to display a summary of all the validation errors occurred in a web page. The error message displayed in this control is specified by the Error message property of each validation control. A Validation control is displayed when the IsValid property of the page is false and if the Error message property of the validation control is not set, no error message is displayed for that validation control. If "Polls" each of the validation controls on the page and aggregates the Text messages exposed by each. It does this through the PageValidator collection. Each validation control is added to this collection. The validationSummary can use this to determines which validators have errors. Properties of ValidationSummary control
Output Summary In this article you learned that how to use the ValidationSummary control in ASP.NET.