CustomLoginButton is used for the same purpose as LoginButton. Only difference is that its appearance is not predefined, but it can be defined with CSS. Login Button class is used to connect a web site to the Facebook and to allow it to use the Facebook API. The example bellow demonstrates login button without style, with defined CSS, as a link, and as an image. For all details about the control, with descriptions of all optional properties, please visit: Facebook Custom Login Button Tutorial.