BLOG = WebLOG
They are similar to a web page except they can be added to by anyone not just the owner. When we went on our 11000 mile trip this past summer, I wanted an online way of letting everyone back home follow us as we went. I went to http://www.blogger.com
and set up a BLOG for our trip. If you go to the link in my signature you'll be taken to our trip BLOG. If you click on the "comments" word at the end, it will then allow you to add your own comments.
BLOGs are used many times like forums to allow anyone to leave comments about something the BLOG owner has written about. Hope this helps.