What is a system call?
A system call is a request made through any program to the operating system for performing tasks, picked by a predefined set, that the said program doesn't have needed permissions to execute into its individual flow of execution. System calls give the interface between the operating system and a process. Most operations interacting along with the system need permissions not available to a user level process, for example: input and output performed with a device present in the system or any form of communication along with other processes needs the use of system calls.