A blog is a user-generated website where entries are made in journal style and displayed in a reverse chronological order. Many blogs give visitors an opportunity to contribute.
The term "blog" is a blend of the words web and log (weblog). A blog is an online diary, defined by the type media used. Many blogs are text-based, but may be constructed with almost any media. A blog consisting of videos is called a vlog; one with mainly photos is called a photoblog; and a blog of audio files is called a podcast.
Blogs are a popular form of information exchange on the Internet today, for just about any subject. A topic list from The Internet Public Library.