A semaphore is a system used to convey information at a distance using visual signals. It often employs flags, lights, or mechanical arms to represent letters or numbers. Semaphore is commonly used in maritime communication, where ships signal each other using flag-based systems to ensure safe navigation. In addition to maritime use, semaphore can also refer to a programming concept in computer science. Here, it is a synchronization tool that helps manage access to shared resources by multiple processes. This prevents conflicts and ensures that only a certain number of processes can access a resource at the same time, enhancing efficiency and safety.