title: Which browsers/plugins block HttpReferer from being sent?
body: <p>I am trying to interpret HttpReferer strings in our server logs. It seems like there is quite a high number of empty values.</p>
  
  <p>I am wondering how many of these empty values are due to direct hits from people entering our URL directly into a browser and how many might be due to some kind of blocking utility that prevents the Referer from being sent.</p>
  
  <p>I really have no idea how many people are using tools or browsers or 'anonymizers' that might block the refer. Any input?</p>