Why do ad manager add a lot of parameters to URLs

It seems that each time I see an ad that is served by an ad manager application there is always a bunch of parameters added to the URL of the product.

Say for instance one random stackoverflow ad : http://ads.stackoverflow.com/a.aspx?Task=Click&ZoneID=4&CampaignID=474&AdvertiserID=5&BannerID=408&SiteID=1&RandomNumber=464183249&Keywords=

or this one:

http://ads.stackoverflow.com/a.aspx?Task=Click&ZoneID=4&CampaignID=474&AdvertiserID=5&BannerID=408&SiteID=1&RandomNumber=2039490120&Keywords=http-1.1%2ccaching%2ccache%2chttp-header-fields%2cheader%2cx-user-registered

If I go with the logic of the things, when you register a click to a banner, you would normally need a few info : "how many times it has been clicked", "by who" (ip/registered account/...), "when".

Now if we look at the parameters there are a lot more informations to this. OpenX adds a lot more on top of that :

http://ox.jeuxonline.info/www/delivery/ck.php?oaparams=2&bannerid=244&zoneid=7&cb=1264705683&maxdest=http%3A%2F%2Fwww.smartadserver.com%2Fcall%2Fcliccommand%2F3141468%2F1264705683

The only reason I can think of this is to save call to the db, other than that I really can't see.

Any hint or ideas ?

Tracking.

The parameters are used to identify you, where you're clicking from, what you're clicking on, which ad campaign your click should go to, etc.