I'm still running into a lot of people who don't know what blogging is. It's important enough you need to form your own opinion on the topic. You may decide it's just so much navel-gazing by a bunch of self-important pretenders.
Or you may decide blogging is the latest evolution of what Gutenberg started way back when.
If you need the basics, I've updated the Blogging 101 post.
Seth Godin has announed that this is "tell a friend about blogs" week. So do it. Tell someone about blogs. Even better, start your own blog!
More on Gutenberg's invention here. Hint: it was not the printing press.