Validator Controld in ASP.NET

ASP.NET provides an easy to use  set of validation controls to check for errors in user input and display messages to the user.

RequiredFieldValidator - Checks validated control contains value.

CompareValidator - Checks user input against constant value, value of another control or for a specified data type.

RangeValidator - Checks if user input is between specified lower and upper boundaries.

RegularExpressionValidator - Checks if user input matches a patter defined by a regular expression.

CustomValidator - Checks user input against validation logic that developer writes.