Blogs come in many shapes and sizes. The present trend is a proliferation of websites that are intended as online journals by which individuals and/or organizations express their thoughts and opinions. That in a nut shell is a Blog. Or to put it another way.
A weblog, which is usually shortened to blog, is a type of website where entries are made (such as in a journal or diary), displayed in a reverse chronological order.
Blogs often provide commentary or news on a particular subject, such as food, politics, or local news; some function as more personal online diaries. A typical Blog combines text, images, and links to other blogs, web pages, and other media related to its topic. Most blogs are primarily textual although many focus on photograph (photoblog), videos (vlog), or audio (podcasting).