The optional access details report keeps track of “user sessions.”  It
will show you detailed “tracks” of the paths taken through your site by
visitors for however many days you specify, and will give you overview
information regarding how many unique visitors you’ve had each day and
how long they seem to be staying around.  If logging of referring URLs
is enabled, it will also show you, where possible, where your visitors
came from.  Please note that precise tracking of the number of visitors
is impossible; the information in this report is at best a reasonably
close approximation based on the information in your server access log.

The optional referring URL report logs the URLs reported by browsers as
the “referers” directing them to the various listed pages.  You should
be aware that this information is far from perfect.  Many browsers do
not provide any information on the referring page; even those that do
can at times provide false or misleading data.  Of course, this report
is only available if your server log contains the necessary information.

The optional keywords report logs the keywords used by your visitors
to find you in the various Internet search engines and directories.  The
major search engines are each listed individually.  Again, this report
is only available if your server log contains the necessary information.

The optional agent and platform reports list the agents (browsers)
and platforms (operating systems) utilized by visitors to your pages.
Again, of course, this report is only available if your server log
contains the necessary information.

(CAVEAT:

(Like any log analysis software, WebLog is based squarely upon
several unfortunately questionable assumptions.  Chief among these
is the assumption that any accesses from a specific IP address
within a reasonably short period of time belong to a single user,
and the assumption that analysis of access logs can actually tell
you anything useful about site visitors, anyway.

(It is possible for different users to access your site with the
same IP address, so a single “user session” might actually reflect
visits from multiple users.  As well, thanks to the number of
systems which now employ local caching, it is quite likely that some
of the pages which seem to be accessed only once are in actuality
viewed many times by many different users.

(WebLog also assumes that the time between the loading of one page
and the loading of the next, so long as it is less than 30 minutes,
is actually spent looking at the first page.  This is clearly not
necessarily the case.  The user could have gotten up to fix himself
lunch or use the bathroom.  He could have reloaded another page
already in his browser’s cache, or could even have gone to look at
pages on other sites before returning to yours.  There is no way of
knowing.

(Finally, WebLog assumes that the average length of time spent
viewing the last — or only — page visited in a user session is 30
seconds.  Again, there is obviously no way to check the validity of
this assumption.)