How do banners ads know where you are?

[osprey4]

I get banner ads here at work that promise low rates for New Jersey drivers like me. I get banners ads at home that sometimes offer services specific to my home town.

So how do banner ads know where I am?

[Siliconjunkie]

http://www.maxmind.com/

[FatalException]

When you access any website or pull up any type of graphic online (including a banner ad), your computer sends its (or its router's) IP address to the server you are requesting data from. That server then responds with the data requested, sending it back through the internet to your IP address. IP addresses are allocated to ISP's and their geographic location is generally known with a reasonable degree of certainty - people in Washington DC might show up as being in Maryland, for instance, but not Kentucky.

For more info about this, check out this site: http://www.geobytes.com/IpLocator.htm

[Siliconjunkie]

your computer sends its (or its router's)

Or proxy if you are using one. Not to nitpick. But, this makes odd things happen. We have users in Canada that use a proxy in Houston or Boston and they see ads for both of them all the time.