Derek’s research is all about discovery. He develops software to help users to discover new music and other media, cultural artefacts such as works of art and architecture, products and services and travel experiences. The software that he develops uses techniques from Artificial Intelligence to make recommendations that are relevant to the user (‘personalised’) and to the context-of-use (‘contextualised’). But good recommendations are typically also diverse, serendipitous and ethical (e.g. privacy-aware), and they are accompanied by authentic explanations. Building software that can satisfy all these demands is Derek’s research challenge.