Gerald Holtom originally designed it for the Campaign for Nuclear Disarmament.
The symbol itself is a combination of the semaphoric signals for the letters "N" and "D," standing for Nuclear Disarmament. In semaphore the letter "N" is formed by a person holding two flags in an upside-down "V," and the letter "D" is formed by holding one flag pointed straight up and the other pointed straight down. These two signals imposed over each other form the shape of the peace symbol. In the original design the lines widened at the edge of the circle. (Thank you wikipedia)
We often take iconic symbols like this for granted, but there are a lot of hours and energy put into the creation of something this simple.
I hope Mr. Holtom is getting residuals on this baby.