What Are Semaphores? Explain In Brief With Two Types Of Semaphores.

Ok :
Semaphore -- a system
A semaphore -- a device or apparatus

Explanation:
Semaphore is a kind of system that is used to signal or convey information. Semaphore is often understood to be the system in which a person holds one flag in each hand, communicating letters or numbers by the position of the flags.

However, a semaphore is a device or apparatus that signals information, often using lights. A stoplight, for example, is a kind of semaphore as evidenced by the Spanish word "semaforo", which means "stoplight". Green means go, red means stop, but yellow (depending on the person as well as multiple other variables) can mean slow down, speed up, or continue doing what you were doing :) (These colors and meanings are based on the US stoplight system).