A string containing the value of the HTTP Referer header. The default value is null.
If the HttpWebRequest.AllowAutoRedirect property is true, the HttpWebRequest.Referer property is set automatically when the request is redirected to another site.
To clear the Referer HTTP header, set the HttpWebRequest.Referer property to null.
The value for this property is stored in System.Net.WebHeaderCollection. If WebHeaderCollection is set, the property value is lost.