Whenever you use a Button or LinkButton it is because you want to be able to do a postback when it is clicked. The same could be the case for CheckBox or DropDownList etc. but then you need to set the AutoPostback property to true. It all works very much the same way from a user’s point of view - click or select and the page performs a postback.
The following LinkButton calls the server-side event handler OnSaveClick.
<asp:LinkButton runat="Server" ID="btnSave" Text="Save" OnClick="OnSaveClick" />
__doPostBack('btnSave ', parameter)
Now the page performs a postback and we can now access the “Hello world!” string that we sent as a parameter from within the OnSaveClick event handler.
protected void OnSaveClick(object sender, EventArgs e)
string parameter = Request["__EVENTARGUMENT"];
In ASP.NET 2.0 you have to set the EnableEventValidation="false" attribute in the page declaration or in web.config to make it work.