A blog is a collection of articles organized with the newest at the top that can be easily updated and allow comments. There are two main types: externally hosted blogs where someone else controls the blog on their server and own/self hosted blogs where the owner controls the domain name, server, and all functions of the blog. Popular externally hosted platforms include WordPress.com, Blogger.com, Typepad.com, Livejournal.com and Blogharbour.com while WordPress.org is a free and popular option for own/self hosted blogs.