Behavioural Insights aim at improving the welfare of citizens and consumers through policies and regulations that are formed based on empirically-tested results, derived using sound experimental methods. Behavioural Insights mixes traditional economic strategies aimed at changing behaviour with insights from psychology, cognitive science and other social sciences to understand how people think, behave and make decisions under different conditions, and uses these insights to improve the design and delivery of programs and services.

A nudge is any aspect of the choice architecture that alters people’s behaviour in a predictable way without forbidding any options or significantly changing the economic incentives. To count as a nudge, it must be easy and cheap to avoid.
— Richard Thaler and Cass Sunstein (2008)