Can anyone tell me about functions of operating systems in computer?

An operating system is a set of programs that control a computer. Usually, an operating system is used to manage all the pieces of a complex system like a computer. The basic task of an Operating system is to keep track of who is using which resource, to grant resources based on a particular request, to account for usage and to mediate conflicting requests from different programs and users. The objective of an operating system is to hide details of hardware by creating abstraction and providing a set of higher level functions. An operating system allows multiprocessing in which two or more processes are executed at the same time. It also involves allocating and often creating a virtual memory for a program. The operating system provides a pleasant and effective user interface. It also maintains a file system in which a user can create, delete and move files around a structured file system. For larger systems, operating system has even great responsibilities and powers. It creates an environment where multiple users can use access the resources of a computer.