Some of the world's biggest social media and tech companies are joining forces to remove terrorist content from their platforms. Facebook, YouTube, Twitter and Microsoft say they'll share technical solutions in what they're calling the Global Internet Forum to Counter Terrorism. Are these social media and tech companies really doing enough to detect and block extremist content? Joining The World Today is David Ibsen, the executive director of The Counter Extremism Project, a non-partisan, international policy organisation formed to combat the threat from extremist ideologies.