The fourth estate:

The fourth estate means the power which is different from government and business group. It can supervise other powers avoid they do something bad for our society. This is media. Although they have this power to supervise other powers, the media have to restrict by themselves. The fourth estate is a strong power because it can spread notions invisibility. Therefore, everybody wants to have a media to convey their thought. For example, KMT and DPP have their own media. They use their media to attack each other and defend themselves.

This photo comes from:

http://editorialiste.blogspot.com/2007/02/how-does-fifth-estate-stand-up-exactly.html

Related Link:

http://www.youtube.com/watch?v=ZNj5rYlzpd4

http://www.idrc.ca/en/ev-116247-201-1-DO_TOPIC.html