This chapter sets the background for when, and discusses the contexts in which, eliciting expert judgements is paramount. The way judgements are elicited and aggregated plays an essential part in distinguishing structured/formal elicitation protocols from informal ones. We emphasise the importance of properly reporting the steps and decision taken during an elicitation, and draw a parallel to the reporting of experimental designs underpinning the data collection. Directions for future research are proposed, and the chapter ends with an outline of the book.@en