People maintained blogs long before term was coined, but trend gained momentum with introduction of automated published systems, most notably Blogger at blogger.com. Thousands of people use services such as Blogger to simplify and accelerate publishing process. Blogs can be described in many definitions and they are all correct.
Blogs are instant publishing. You write, you cut-and-paste images, you cut-and-paste links, you customize everything through a WYSIWIG (what you see is what you get) interface, and with one click you publish your information or article.
A frequent, chronological publication of personal thoughts and Web links.
A blog is often a mixture of what is happening in a person's life and what is happening on Web, a kind of hybrid diary/guide site, although there are as many unique types of blogs as there are people.
Blogs are alternatively called web logs. However,"blog" seems less likely to cause confusion, as "web log" can also mean a server's log files.