This book offers the first systematic review of the structuralism of physical theories. Particular emphasis is placed on the inclusion of empirical imprecision into formal reconstructions of theories. The proposed measure of imprecision allows for a topological comparison of theories. Considering the ongoing debates on the nature of the thermodynamic limit in statistical mechanics, as well as on limit relations between classical and quantum mechanics, the author asserts that the Bourbaki-style structuralism, together with E. Scheibe's theory of reduction, is the best choice for reconstructing and analyzing the related questions of reduction and emergence. Readers will appreciate the critical overview of the main positions in philosophy of science, examined with particular attention to their applicability to current problems of fundamental theories of physics.