“Normally Apache logs all requests in its access log. In certain
cases this can distort your page view statistics (if you use a tool
like Webalizer or AWStats that creates statistics based on Apache’s
access log), for example if you get lots of visits from search
engine spiders or from a certain IP address (e.g. your own), or if
each of your pages includes another page (e.g. in an iframe) from
your web site (that would instantly double your page views which is
obviously not correct). This short guide shows how you use Apache’s
SetEnvIf directive to prevent Apache from logging such
requests…”