"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 is a frequently updated, personal website featuring diary-type commentary and links to articles or other Web sites. Blogs range from the personal to the political, and can focus on one narrow subject or a whole range of subjects.
Many blogs focus on a particular topic, such as web design, politics, sports, or mobile technology. Some are more eclectic, presenting links to all manner of other sites. And others are more like personal journals, presenting the author's daily life and thoughts.
Generally speaking (though there are exceptions), blogs tend to have a few things in common: