Final answer:
Semaphores are used mainly for IPC mechanisms in concurrent systems or multi-threading environments to control access to shared resources, offering synchronization and preventing race conditions.
Step-by-step explanation:
Semaphores are primarily used to implement IPC mechanisms (Inter-Process Communication). These are synchronization tools that help control access to shared resources by multiple processes in a concurrent system or a multi-threading environment. A semaphore can be thought of as a counter that is used to signal whether a particular resource is available or not. To access the resource, a process must 'wait' or decrement the semaphore, and upon finishing using the resource, the process will 'signal' or increment the semaphore. This mechanism ensures that critical sections of code are accessed in a controlled manner, preventing race conditions and ensuring data integrity.