What's the proper way to do form validation in C#? [duplicate]

This question already has answers here: 开发者_如何学JAVA Closed 12 years ago.

Possible Duplicates:

WinForm UI Validation

What is the best way to do validations in windows forms

I'm writing an application in C# that has a large number (>30) of forms (TextBox, RadioButton, and CheckBox) that span a wide variety of data types and I was wondering what the proper way to validate them all would be. Also, not all of the fields are required.