Operating systems are the set of programs. It can manage computer hardware resources. It provides services for application software. It is the most common type of system software. Time sharing operating systems are more efficient. It is used for accounting such as processor time, printing, mass storage and many more resources. The operating systems are an important role between the computer hardware and the application programs. Operating systems are found in cellular phones, video game consoles, super computers and web servers. Some of the modern operating systems include Linux, Android, iOS and many more. There are many types of operating systems available such as real time operating system, multi tasking operating system, multi user operating system, distributed and embedded operating systems. It consists of many parts. The main component of operating system is kernel. It is used to control low level processes. Digital Equipment Corporation is developed in many operating systems.