Communities are keen to prioritise the redevelopment of brownfield sites to prevent unnecessary loss of green space or other harmful development, or to remove neglected eyesores. Brownfield land is, broadly speaking, land that has previously been developed, as opposed to greenfield land, such as countryside, Green Belt, parkland or greenspace, which has never been built on. This toolkit aims to facilitate the redevelopment of brownfield land by helping people to tell their local council about brownfield sites that might be developed, and to get them included in their Brownfield Registers (and other Land Supply datasets). It enables citizens to start to convert their 'lay' knowledge from lived experience into the kind of technical information required by spatial planners, providing an interface between two knowledge types.