On 21 October 1983, the General Conference of Weights And Measures adopted the value of 299,792.458 km/s for the speed of light. At the occasion of the anniversary, hundreds of activities are voluntarily organized over more than 30 countries in the world and encompass all kinds of demonstrations and discussions on the impact of photonics on our day-to-day life. Any company, research organization, university, school, student chapter is encouraged to organize an activity.