In the 2014 Tam Dalyell Lecture, Professor Harald Haas, Chair of Mobile Communications at The University of Edinburgh, reveals an amazing innovation that could change wireless communications forever. The Li-Fi system uses standard light-emitting diodes (LEDs) to transmit electronic data signals, which will enable users to access the internet through the ordinary lighting systems in schools, workplaces and homes. This revolutionary invention has the potential to bring cheap, energy efficient and super-secure wireless access to the world. Recorded on Sunday 13 April at the University of Edinburgh's Playfair Library.