It is like your own personal message board subject that is titled with your name or alias that only you can write to. So is it is basically a public electronic log/diary composed of stuff that you wrote. In the case of Susan's link it is the writings of an Iraqi in Baghdad.

If you wanted to start one, you would just go to a website that hosts that type of "message board" and open an account. Then you could start your Debbie in Belize Blog or what ever which would make you blogger. Point your friends at the link and they could keep up to date on your exploits no matter where you or they ended up...