services provided by OS.

Following are a few common services provided by an operating system:

Program execution: The system must be able to load a program in memory into
memory and to run that program. The program must be able to end its execution
either normally or abnormally.

I/O operations: A running program may require I/O. OS must provide a means
to access I/O devices to perform I/O.
File System manipulation: Program needs to read a file or write a file. The
operating system gives the permission to the program for operation on file.
Operating System also provides an interface to the user to create/delete files and
directories.

Communication: OS provides two techniques; shared memory & message
passing to facilitate communication among processes which may be running on
the same computer or may be running on different computers which are
connected over a network.

Error Detection: The OS constantly checks for possible errors in the working of
software programs and hardware components. The OS takes an appropriate
action to ensure correct and consistent computing.

Resource Allocation: In case of multi-user or multi-tasking environment,
resources such as main memory, CPU cycles and files storage are to be allocated
to each user or job. The OS is a manager of all kinds of resources in the computer
system and it uses different schedulers for doing resource management.

Protection: The OS ensures that all access to system resources is controlled and
protected from invalid access attempts. The access to various resources is
granted only after user authentication.