''A blog (a portmanteau of the term web log) is a discussion or informational site published on the World Wide Web and consisting of discrete entries ("post") typically displayed in reverse chronological order (the most recent post appears first).'' Source

''Blog' is an abbreviated version of "weblog," which is a term used to describe web sites that maintain an ongoing chronicle of information. A blog features diary-type commentary and links to articles on other web sites, usually presented as a list of entries in reverse chronological order. Blogs range from the personal to the political, and can focus on one narrow subject or a whole range of subjects.'' Source  

''A blog is a 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". Blogs are typically updated daily using software that allows people with little or no technical background to update and maintain the blog. Posting on a blog are almost always arranged in chronological order with the most recent additions featured most prominently.'' Source