[masraum]

Keith pretty much said it. Any and every device on the Internet or pretty much any network these days is going to have an IP address. (IP = Internet Protocol)

You can't take your IP address with you when you move around, ie work to home, home to starbucks, work to hotel, hotel to airport. Everyplace you go you'll probably get a different IP address.

As Keith said, the IP address at work and your house probably won't stay the same forever. (well, it could, but these days that's not the norm)

So, an IP address is not necessarily a good way to track someone on the Internet.

Another thing. When I surf the net from work, everyone in my building (5 floors) all appear to have the same IP address when we are on the net. All of our PCs and Phones have unique addresses within the building, but when any traffic goes to the Internet those unique addresses are masked and look like a single address.