Do a Google image search for protest symbols and your first page will show a range of raised fists, Guy Fawkes masks and possibly even a few giant inflatable rats. But by far the single most represented image you’ll see is the peace sign. It is probably the most famous protest symbol in the world and has its origins in the British anti-nuclear movement of the 1950s. The sign represents the semaphore signals for two letters: ‘N’ (the two diagonals pointing down) and ‘D’ (the vertical line that divides the circle), which together represent nuclear disarmament. It has become the symbol of anti-war and social justice movements across the globe.