 <p>If you set <code>cookieless="true"</code> (or <code>UseDeviceProfile</code> and browser has cookies disabled) in your <code>web.config</code> file, <a href="http://msdn.microsoft.com/en-us/library/aa480476.aspx" rel="nofollow noreferrer">authentication</a> information is appended to the URL and this url will be valid across other browsers. If you use cookies to identify users, then only the current browser will have the user authenticated.</p>