Final answer:
A signal in operating systems is used to notify a process of events without employing priorities, differing from hardware interrupts and often used for inter-process communication.
Step-by-step explanation:
A signal is a mechanism used in operating systems to notify a process that a particular event has occurred. Unlike hardware interrupts, signals do not have priorities and are typically used for inter-process communication or to indicate events such as division by zero, segmentation faults, or to instruct a process to terminate.
In many operating systems, signals are identified by integers and can be sent to processes within the same system by the kernel, by other processes, or manually by the user.
Signals are an important concept within Unix and Unix-like operating systems, where they provide a simple way to deliver notifications to a process that an event has occurred, often requiring the process to interrupt its current activity and handle the signal—either by performing a default action predefined by the system or by catching the signal with a user-defined handler.