What is a Blog?

I started at the Oxford English Dictionary. The OED claims that "blog" was first used in 1999, but for a complete definition of the word, it sends you to "weblog." This word was first used in 1997 as is defined as

"A frequently updated web site consisting of personal observations, excerpts from other sources, etc., typically run by a single person, and usually with hyperlinks to other sites; an online journal or diary." 

The first half seem accurate, but the "online journal or diary" seems to be increasingly less accurate. Litblogs, in my experience at least, contain smatterings of personal bio, but, for the most part, stick to linking, specific opinion giving, and critiquing - emo is nowhere to be found. But I want to pick apart this definition in posts to follow...