The user connects to the Internet and \"Runs\" the software as and when needed from a cloud server, perhaps even storing their files in the cloud too OS other operating system. The OS handles the links between hardware, the CPU, memory, hard drive, peripherals such as printers and cameras as well as the components. The paper is focus on various issues characteristics of cloud Operating System (OS). This paper also Focus on requirements of cloud OS. In this paper, the authors know about many different OS which is used by own in daily bases. This paper shows list of various cloud operating system. They define different cloud operating system separately.