Website Stats - Why some visitors have no refererer

Why is it that some visitors don't have a refererer? Can tools be downloaded and installed on web browsers to mask or hide the page that they enter your website from?

 

They just type the address directly into the browser, hence no referrer

 

Or: Install a firewall like Norton Personal Firewall that blocks that information by default.

 

Also, there's a very popular Firefox plug-in that lets you surf without sending the Referer [sic] HTTP header. If you see a visitor with a Firefox User-Agent but no referrer, that might be why.

And of course, spiders masquerading as regular MSIE browsers don't send referer headers (at least not that I've every seen.)

LC88

 

So, what if everyone starting using these? Wouldn't that make website statistic software obsolete?

 

Not really. Web stats track lots of other things besides referrers. Plus, most serious e-marketers also buy traffic through PPC (e.g. AdWords), where the landing page URL provides indication of referrer, so in that case you don't need to look at the 'real' referrer info.

LC