Could someone explain to me the concept of Google latitude?

I have a verizon wireless w/ internet. I saw this app on the web so technically I have to try it out cause its free, but I'm stuck in signing up so could someome explain to me how to use Google latitude.Could someone explain to me the concept of Google latitude?
Hello

On this page you'll get

the requested information.



http://www.chrisbrogan.com/google-latitu鈥?/a>

stella mccartney