The word "blog" is a truncated form of the expression "web log." This expression refers to websites, especially personal websites, that publish discrete "entries" and display them in reverse chronological order.
WordPress.org describes a blog as "maintaining an ongoing chronicle of information" through commentary that resembles a journal and includes links to articles on other websites. Although they evolved from online diaries, blogs deal with a wide variety of subject matter, ranging from politics to hobbies and niche interests. Some blogs have multiple authors, and many popular ones are professionally written and edited. As of 2014, two popular blogging websites are Tumblr.com and Blogger.com.