Our society is struggling with a large number of derogatory rumours that threaten economies, democracy and cybersecurity. A major source of rumours comes from social platforms due to their lack of information authentication. While rumours can have severe real-world implications, their detection is notoriously hard: content on social platforms is brief and lacks semantics; it spreads quickly through a dynamically evolving network; and without considering the context of content, it may be impossible to arrive at a truthful interpretation. In this chapter, we harness the advances of big data and artificial intelligence models for early detection of rumours before the damage is out of control. Successful rumour detection prevents deceptive content from polluting our social media and restores public’s trust.