Navigates backward one item in the history list.
This method has no parameters.
During a browsing session, the WebBrowser control and Windows Internet Explorer maintain a history list of all Web sites visited during a session, unless you specify the navNoHistory flag when you use the Navigate method.
Use the CommandStateChange event to check the enabled state of backward navigation. If the event's CSC_NAVIGATEBACK command is disabled, the beginning of the history list has been reached, and the GoBack method should not be used.