SPUG: Web Bugs

[Colin Meyer]

Doug,

On Mon, Aug 20, 2001 at 08:27:37PM -0400, Doug Beaver wrote:
> 
> What is it about transparent gifs (whether they are static or generated
> by a cgi) that makes it easier to log and retrieve page view data?  I am
> trying to see the benefit, but I can't.  Can you explain a little more?

Imagine an html attachment to an email that somewhere includes the image:

<img src="http://emailtracker.com/images/invisi.gif?uid=20010820202737.A78384@beaver.net" />

Anyone who views the html attachment with a browser that automatically
fetches all images will have inadvertently logged the fact (in
emailtracker.com's web access.log) that this html attachment has been
read from their particular ip address.

That the gif happens to be tiny and transparent makes it not so noticeable
to the typical user.  Insidious.

Have fun,
-C.

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