 In this section, we survey the results and motivations of the shape dynamics research program, focussing first on the above-mentioned theory of Barbour and Bertotti (which recovers a subsection of the solution space of Newtonian particle theory), before turning to the Machian alternative to general relativity developed by Barbour and collaborators: it is this latter theory which is shape dynamics ‘proper’. Readers uninterested in the technical details of this work can skip to section 3.5, in which its conceptual upshots are discussed.