What's a blog?
According to wikipedia a blog is

a website where entries are written in chronological order and commonly displayed in reverse chronological order. "Blog" can also be used as a verb, meaning to maintain or add content to a blog.

While that definition is true it's not the whole story. Blogs can and are just about anything you imagine. They are personal websites where individuals write about their lives and families. They are business websites where companies write about what's going on with their company. They are collections of links from other sites on the internet. They are websites with multiple writers about politics and current events. They are showcases for art work. They are the manifestations of business concepts. They are businesses themselves. They are anything you can imagine them to be.