According to Oxford Dictionaries, the meaning of the word blog is "a regularly updated website or web page, typically one run by an individual or small group, that is written in an informal or conversational style." Many call the author of blogs a "blogger."
Blogging has also become a popular search engine optimization (SEO) tool because search engines like Google and Yahoo know that a blog is frequently updated with content or visitor comments. Many popular companies use blogs or bloggers to sell products because they attract daily viewers.
The term "vlog" was developed from blog. It refers to a blog done via video instead of in a written format.