1. noun. A contraction of weblog, a form of on-line writing characterised in format by a single column of text in reverse chronological order (i.e. most recent content at the top) with the ability to link to individual articles. There is usually with a sidebar displaying links, and the content is frequently updated.

(probably coined by Peter Merholz)

Usage: "Glenn has writen an interesting article about the folly of gun control on his blog"

also see: Warblog, Journal blog, Pundit blog, Tech blog, Group blog

2. verb. To write an article on a blog.

Usage: "Steven Green has just blogged about the joys of Vodka today"

or

"After reading that crap in the New York Times about globalization, I feel a serious need to blog about real world economics"

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The majority of blogs are non-professional (update July 2004: commercial blogs of various sorts are now appearing in increasing numbers) and are run by a single writer. However whether or not a blog has a single author or is a group effort, a key differentiating factor between a blog and other on-line formats (such as forums, wikis etc) is that the main articles (as opposed to just comments) are written by the blog's owners/members and not by the general public.

Although there are several competing definitions regarding what makes a blog a blog, it can be convincingly argued that, circa 2004, for something published on the web to be a true blog, it must be configured to be readily accessible by the blogosphere. That means although reverse chronological order is a defining feature of a blog, that alone is not enough. If the individual articles cannot be linked to separately via a permalink (rather then just linking to the whole site), then the site in question is not a blog.

This means some ostensible blogs are debatably not really blogs at all (they are merely 'blog like' in appearance) by what the developing understanding of what a blog really it.

For example the Guardian, a British broadsheet newspaper, has two blogs and prides itself that it 'gets' blogging. However whereas the Guardian Online Blog, which deals with technology, is indeed a blog (and quite a good one), the Guardian main blog, called simply The Weblog¹, is nothing of the sort as you cannot link to individual articles and hence it is not actually part of the blogosphere. Not surprisingly as a result 'The Weblog' is largely ignored by other blogs and hardly ever linked to according to the various monitoring services such as Technorati or Blogstreet).

¹ = as of late 2004, 'The Weblog' was superceded by Newsblog, which is a proper full featured blog