A policy is a set of related decisions which give rise to specific proposals for action or to negotiated agreements. These decisions may relate to single issues such as the imposition of regulated limits on chemical discharges into a water body; or to issues which are far broader in scope such as the creation of a new national park or a local enterprise partnership, or a state‐wide system to provide care for the elderly. For these broader issues, the challenge for policymakers is to ensure that the decision‐making process effectively meshes different types of knowledge such as scientific knowledge, knowledge of the local context and wider knowledge of what has worked in the past; and to do this whilst involving different types of organisation such as line ministries, research providers, non‐governmental organisations, advocacy groups, local delivery bodies and citizens. Supporting this complex decision‐making process often requires people and organisations able to
facilitate the links between these different groups; working as neutral intermediaries to translate and ‘broker’ different types of knowledge so that current policy decisions are based on the best available knowledge.