The whitepaper has three parts. The first part provides some contextual background, describing the diverse range of online services utilised by terrorists and extremists and the process by which propaganda is disseminated online. The second part details industry responses. As well as referrals from users and law enforcement, it describes the use of AI for proactive detection and collaborative, cross-platform initiatives. The third part describes four issues for discussion: transparency; definitional clarity; the impact on those targeted; and, the use of online data for predictive purposes.