A blog (short for web log) is a website where entries are written in chronological order and displayed in reverse chronological order.
Blogs provide commentary or news on a particular subject such as food, politics, or local news; some function as more personal online diaries. A typical blog combines text, images, and links to other blogs, web pages, and other media related to its topic. The ability for readers to leave comments in an interactive format is an important part of many blogs. Most blogs are primarily textual, although some focus on photographs (photoblog), sketchblog, videos (vlog), music (MP3 blog), or audio (podcasting), and are part of a wider network of social media.
The term "blog" is a portmanteau of the words web and log (Web log). "Blog" can also be used as a verb, meaning to maintain or add content to a blog.
-Wikipedia (May 28, 2007)