The Internet has become a deeply ingrained in the lives of most Americans. It looms so large, in fact, it is easy to imagine that it is immune to change — that it will always remain the free and open medium that it is now. But there are no such guarantees. The Internet is a human institution, operated by real individuals and companies, and like most human institutions it is not static and unchanging. In fact, the history of the Internet as a mass public communications medium has been marked by two stages — and ongoing changes to the underlying architecture of the Internet, combined with a recent landmark court decision, may now be bringing us into a third stage.