Details of User Tracking
None of the code I'm using on this site performs any user tracking unless the user specifically opts to be tracked.  (My hosting service, phpwebhosting.com, may track your visit, however.  If you're concerned about that you should check their Privacy Statement.)
The advantage to being tracked is that the site can tell which photographs have been added or updated since your last visit.
Your ID string
You can specify any text that you like as your Site ID String.  I recommend you use your full name or your email address, both of which are (usually) easy to remember.  Of course, you'll have to enter the same Site ID String each time you use the tracking feature, otherwise you're defeating it's purpose.  For that reason, I've provided the "Remember me" feature.  If "Remember me" is checked, the site will drop a cookie containing your Site ID String onto your machine.  (If you subsequently log on from a different machine, or the cookie can not otherwise be found, you will, of course, have to re-enter your Site ID String.)  If "Remember me" is not checked, the site will not drop such a cookie -- in fact, it will attempt to remove any cookie that it may have previously dropped onto your machine.
Immediately after processing the "Remember me" feature, your Site ID String gets hashed (read on).  I only store the hashed version in the site's database.  If you use your email address as your Site ID String, I will not use it to send you email, nor will I release it to anyone else.
Site ID Strings submitted to this site never actually get stored on the server.  Instead, a Site ID String such as "email@example.com" immediately gets converted to something like "92d2ed12dcb2cce2cc92f0200200c04fe" before I store it anywhere.  I use a popular one-way hashing algorithm called "MD5" to accomplish such conversion. The algorithm is called "one-way" because, although the scrambling operation is quick and easy, the reciprocal operation (unscrambling) is believed to require tremendous amounts of time and computing power.
$Id: user-tracking.phtml,v 126.96.36.199 2001/08/12 22:29:02 kevinanlipscomb Exp $