What is a Blog?

What exactly is a blog?

We start out with a definition from Wikipedia - Blog - Wikipedia, the free encyclopedia

What is a weblog? A weblog, or blog, is a personal journal on the web. Weblogs express as many different subjects and opinions as there are people writing them. Some blogs are highly influential and have enormous readership while others are primarily intended for a close circle of family and friends.

The power of weblogs is that they allow millions of people to easily publish their ideas, and millions more to comment on them. Blogs are a fluid, dynamic medium, more akin to a 'conversation' than to a library — which is how the Web has often been described in the past. With an increasing number of people reading, writing, and commenting on blogs, the way we use the Web is shifting in a fundamental way. Instead of being passive consumers of information, more and more Internet users are becoming active participants. Weblogs let everyone have a voice.
(From Technorati)