About Semaphore

Semaphore is a alphabet, the same way Morse and Braille are alphabets. Semaphore is a convention to convey letters by the means of two flags. For a letter, the flags are held differently, as you can see by the chart below. The person who holds the flag to spell out the words is called the signaler.
Albert Kirsch said, "What gives semaphore flags content is not their design at all, but rather their position! A signalman without flags could still just wave his arms and get his message across; the "flags" just add visibility."

So really, the flags are just there to add visibility so the person you're sending the signals to can see the message better.