How to enter only characters in a TextBox in asp.net?

Suppose we have a TextBox named First_Name and we want to validate it in such a manner so that user can enter only characters in a TextBox.

We can use RegularExpressionValidator to validate First_Name. We just need to set the following  RegularExpressionValidator properties:

ID	FirstName_Validator
ControlToValidate	First_Name
ErrorMessage	First Name is a character field.
ValidationExpression	^([A-Za-z])+$

Now if user enter any value in a First_Name TextBox other than characters, it will show an error message.

(Note- You can write your own Error Message and Control Names.)