Plan 9 from Bell Labs is a free software distributed operating system. It was made for research purposes as the successor to UNIX by the Computing Sciences Research Center at Bell Labs during the late 1980s. Plan 9 is currently used as a hobbyist's operating system, and in certain experimental fields, where the highly distributed nature of the operating system is valued. Plan 9 has novel features such as the 9P protocol for accessing local and remote resources as files, union mounts, an improved proc file system, and native unicode support throughout the system. In Plan 9, all system interfaces, including those required for networking and the user interface, are represented through the file system rather than specialized interfaces. It also has a graphical user interface built in, called rio, in anticipation of the graphical world.