What is a blog for?

I have many friends whose blogs I thoroughly enjoy reading. I want a blog, I want people to enjoy what I write, but I really have the feeling that this is not what blogs are for. It should not be a diary, it should not have TMI, it should not be solely to garnish attention. A thoughtful narrative of life? A way for people to keep up? A way to share praise and worship? I don't know. So here's my next attempt at blogging.... we'll see how long this one lasts before I delete it.