fourth estate

It might be news to you that the term fourth estate has been around for centuries. In Europe, going back to medieval times, the people who participated in the political life of a country were generally divided into three classes or estates. In England they were the three groups with representation in Parliament, namely, the nobility, the clergy, and the common people. Some other group, like the mob or the public press, that had an unofficial but often great influence on public affairs, was called the fourth estate. In the 19th century, fourth estate came to refer exclusively to the press, and now it's applied to all branches of the news media.