Validation occurs in response to an event. Most of the time you will see it is a Button Click event. When you drag and drop a Button Server Control onto your form its gives you the following code:
<asp: Button ID=”Button1” runat=”Server” Text=”Button”/>
Here when you see the properties of the Button Control, you will see that the CausesValidation property is set to True.
If you have multiple buttons on an ASP.NET page, and do not want every button to initiate the form validation, you can set the causesValidation property to False for all the buttons you want to ignore in the validation process:
<asp:Button ID=”Button1” runat=”server” Text=”Cancel” CausesValidation=”false” />