SUMMARYProcedures have been developed whereby the topological properties of single‐phase cell structures, and two‐phase structures, may be estimated from a series of closely spaced microsections. In both cases, the analysis is straightforward but tedious. However, because the topological properties abstract a description of the basic skeleton or framework of the structure from details of shape and size, their quantitative knowledge provides insights into microstructural behaviour that may be obtained in no other way. These combined factors make it likely that the application of these procedures will be limited to very select problems, but that where they are applied the results will significantly affect the thinking in the fi