What is a blog?

Originally short for "weblog", a blog is just a web page that contains entries (or "posts") in reverse chronological order, with the most recent entry on top. But blogging has taken off because the explosion in blogging software and services -- like Blogger, TypePad and WordPress -- has turned blogging into one of the easiest ways for people to maintain a constantly updated web presence. In addition to the classic text blog, we now have photoblogs (consisting of uploaded photos), audio blogs (a.k.a. "podcasts") and video blogs (which consist of regularly uploaded video files).

One of the most powerful aspects of blogs is their audiences' ability to interact with the blog's author and each other. Most blogs (according to some people, all real blogs) allow readers to leave comments on each post, and on many blogs the discussion gives rise to a thriving community.

Communities arise among blogs as well. Bloggers often link to each others' posts and offer their views on them, and a technology known as trackback shows who's linking to a given post.