What is blogging to me?

As I am new to the blog world, I decided to do some research on blogging. The most basic definition I found for a blog was from the glossary on www.matisse.net. It is:

A blog is basically a journal that is available on the web. The activity of updating a blog is "blogging" and someone who keeps a blog is a "blogger." Blogs are typically updated daily using software that allows people with little or no technical background to update and maintain the blog.

Postings on a blog are almost always arranged in chronological order with the most recent additions featured most prominently.

Although somewhat restrictive, for the most part it sounds pretty simple right? If you are like me, then maybe it doesn't sound so easy.
After setting up this blog, I realized that to keep a blog you really need to have some sort of focus, in other words, what will your blog be about?
Now I'm thinking, how do you narrow that down? There are millions of reasons why people blog.

For example:
A blog about family, with pictures, videos and/or written updates. This type of blog usually caters to family.
A blog used as an online journal or diary.
A blog to maintain articles, papers or general writing. Something like an online resume.
A blog for celebrity gossip, like Perez Hilton, which caters to anyone who's interested in daily updates on celebrity life.
A blog for work, or for a job. This usually involves writing articles that are conducive to the company they are working for or maintaining a blog to advertise for these companies or websites.
"How to" blogs.

Like I said there are blogs for almost anything you can think of. So what is my focus? What is this blog centered on?
I love to write. In fact, I have written over 250 reviews, mostly on books, movies and skin care products. I want one place to keep these reviews. Sort of a list of accomplishments, as well as one place I can refer back to. I also enjoy writing for the sake of writing.
This blog will always be a work in progress, but for me it will be a place for me to retain my reviews and a place for me to write.
Now I think I've got it. Not too hard after all.