Operating System (sometimes abbreviated as "OS") is the program that, after being initially loaded into the computer by a boot program, manages all the other programs in a computer including application.
Haiku is an open source operating system currently in development that specifically targets personal computing. Inspired by the Be Operating System, Haiku aims to become a fast, efficient, simple to use, easy to learn and yet very powerful.
More info? Visit Haiku
Want to try? Download Here