What are system calls in an operating system?

System calls serve as the programming interfaces through which application programs can request services from the operating system. They allow user programs to interact with the underlying system resources such as files, processes, and hardware components. When a program needs to perform an operation that requires OS intervention—like reading from a file or allocating memory—it makes a system call. This sets up a controlled environment where the operating system can safely execute the required operations on behalf of the user application.

By utilizing system calls, applications can leverage the functionalities provided by the operating system while remaining abstracted from the complexities of hardware interaction and low-level resource management. Each system call typically corresponds to a specific function within the OS, thereby facilitating the process of resource management and ensuring security and stability in the execution of programs.