Not sending a referer can sometimes break sites though. For example some image hosting sites will not display content if you are not coming from their domain (t

Not sending a referer can sometimes break sites though. For example some image hosting sites will not display content if you are not coming from their domain (to avoid hotlinking) and some web-apps will kill deep linking like this. Granted it is not very secure but some people will go to great lengths to break the open web. This is also how Google Analytics knows where people come to your site from, for example.