A blog is the shortened form of weblog
A weblog is a diary of a writer (called a blogger in this case). On the weblog, several topics can be discussed, one blogger writes what he has experienced that day, the other one has a certain subject on which to write. The most recent topic is listed first on the weblog, follow older posts. Usually it is also possible to respond to the messages that are written, thus creating interaction between the blogger and the visitors of the weblog. This site also uses blog software and is in essence also a weblog. Messages are posted, you can reply to the messages, and the most recent message is at the top.