A blog is a regularly updated website that reports news such as the latest update, activities and promotions. Blogs are often maintained by an individual or small group, that is written in an informal or conversational style.
To get the sense of blogs, you can think about how a news work on 20th and 21th century. In the 20th century, news are produced by professionals, then they broadcast them to the public media such as TV, Radio and newspaper. The 21st century marked the point, where news became both professional and personal. News is no longer limited to mainstream stories like world, sports, politics and financial; individual are free to write anything they like such as personal interest, review, opinion, and industry news.
Here is a short video presentation of what really a blog is.
As described by the short video presentation, a blog can be owned by anyone. It can tackle virtually everything depending on the interest of the author/blog owner. It can also be used in marketing and brand exposures (which is one of the best ways in internet marketing). In general, a blog serves as a channel or gateway of anything on the web.