Cookies are used to store data that's about the person that just visited your site and did something.
With shopping carts you can remember them next time they come and say, ok you bought this and that, then display information based on what they bought, If the buy fishing poles then they might be scared off of your home page next time becuase it's all computer hardware. Next visit after they dug out what they wanted and bought it, you can show them information right on your home page and advertise products directed to them about fishing stuff.
Get it?
Targeted Audience. This way you get to target them all. Advertisers like to target an audience becuase they get more hits for their money. If you advertise for everyone on your site that's a pretty big variety. Set aside the fishing guys and you can advertise fishing pole companies all day.
perlkid [sig][/sig]