Do we need a definition for Web logs?

Like many, I read the comScore report that said one in six Americans visit/read blogs, among other things.

Now, also like many of you, there's been some conflict about traffic to blogs, and blog ranks. I'm not going into that.

What got me thinking was the line in the introduction (page 2, 2nd paragraph) that "it is likely that a certain number of people in a survey regularly visit specific sites without realizing that those sites would be qualified as "blogs," and so they neglect to identify themselves as blog readers."

Does there need to be a definition of what a blog is?

I visited some of the "blogs" that were ranked high. Many, like the R- or worse rated fark.com doesn't seem like a blog. It has too many internal links on the left side, and seems like a regular Web site.

Should a blog be pretty basic, simple? Shouldn't a blog contain the owner's comments, opinion, links to information, other sits, and maybe a little about the owner?
Too much more than that, than it's not a blog. Right?

Am I off?

Isn't there some unwritten but commonly accepted definition of a blog?

If not, there should be.
-- Michael