Context switching is a technique used by the operating system to switch a process from one state to another to execute its function using CPUs. It involves saving the context or state of a running process so that it can be restored later, and then loading the context or state of another process and running it. Context switching is a feature of a multitasking operating system and allows a single CPU to be shared by multiple processes.

The need for context switching arises because one process does not directly switch to another within the system. Context switching makes it easier for the operating system to use the CPU’s resources to carry out its tasks and store its context while switching between processes. There are three major triggers for context switching: multitasking, interrupt handling, and user and kernel mode switching.

In summary, context switching is a crucial mechanism in operating systems that allows multiple processes to share a single CPU. It involves saving the context of a running process, loading the context of another process, and running it. The need for context switching arises because one process does not directly switch to another within the system.