When you think of social media, you are likely to think of computers, mobile devices and sites like Facebook or Twitter. But there is one form that pre-dates it all - street art has been with us for centuries. Street art, graffiti, came before television, radio and the printing press and remains a powerful tool of communication. The medium was used to great effect during the Arab revolutions, acting as an indicator of what people in the street were saying. Street art is the political warning sign that tends to appear and attract attention long before the acticists actually hit the streets. And while demonstrators may have gone back to their lives after the fall of a government, street artists remain, making the most out of their new found freedom of expression, hoping that it lasts. In this week's feature, Listening Post's Meenakshi Ravi looks at political street art, the low-tech end of social media.