-> In order to validate user input, ASP.Net provides validation server controls. All validation controls inherits from BaseValidator class which contains the common validation properties and methods like ControlToValidate, Enabled, IsValid, EnableClientScript etc.
RequiredFieldsValidator – validates compulsory/required input.
RangeValidator – validates the range. Validates that input falls between the given range values.RegularExpressionValidator – validates input value against a defined regular expression pattern.