According to http://www.computersprintersrepairshouston.com/glossary_of_terms.html the term blog comes from the term "Web log." A blog is basically a journal that is available on the web. The activity of updating a blog is "blogging" and someone who keeps a blog is a "blogger."
A blog is a website in which items are posted on a regular basis and displayed in reverse chronological order. The term blog is a shortened form of weblog or web log. Authoring a blog, maintaining a blog or adding an article to an existing blog is called “blogging”. Individual articles on a blog are called “blog posts,” “posts” or “entries”. A person who posts these entries is called a “blogger”. A blog comprises text, hypertext, images, and links (to other web pages and to video, audio and other files). Blogs use a conversational style of documentation. Often blogs focus on a particular “area of interest”, such as Washington, D.C.’s political goings-on. Some blogs discuss personal experiences.’
