I stole this description from the "Blogger" website:
A blog is a personal diary. A daily pulpit. A collaborative space. A political soapbox. A breaking-news outlet. A collection of links. Your own private thoughts. Memos to the world.
Your blog is whatever you want it to be. There are millions of them, in all shapes and sizes, and there are no real rules.
In simple terms, a blog is a web site, where you write stuff on an ongoing basis. New stuff shows up at the top, so your visitors can read what's new. Then they comment on it or link to it or email you. Or not.
In other words, for me it is a personal journal of whatever topic you choose to post on. For example, you could start a blog topic related to building a bow or going on a fishing or hunting trip. You would pst updates to the blog and people can read it and comment on it if desired.
So, in some ways it is similar to the forums like we are using now but presented in a different manner. Take a look at the Blog KC started called "Lost it"... Basically he has started a journal of his trip to Chitown... You can post comments and others can see the comments.
Kind of like a forum thread that you started that only you can post to and that others can read and comment on.
I am rambling....