Define System Call
A system call is a request that is made by any program to the operating system for carrying out tasks - picked from a predefined set - which the said program does not have needed authorizations to execute in its own flow of execution. System calls offer the interface among a process and the operating system. Several operations interacting with the system need permissions not available to a user level process, for example I/O performed with a device present on the system or any form of communication with other processes needs the use of system calls.