A linkage is an assembly of coupled bodies or links whose freedom of movement is restricted, after the fixture of one link, by the constraint imposed by their couplings. Frameworks and mechanisms are particular types of linkage. In this article the freedom on a plane or in space of linkages of an unlimited complexity is investigated by a general method whose application can readily be extended to space of four or more dimensions. The results obtained permit the analysis of any given linkage by mere substitution in the appropriate formula; but although the results are primarily intended to assist the analysis of existing linkages, it is shown how they can be used to a limited extent in the synthesis of new linkages to meet given requirements.