Systems displaying competing interactions of some kind are widespread - much more, in fact, as commonly anticipated (magnetic and Ising-type interactions or the dynamics of DNA molecules being only two popular examples). Written for researchers in the field with different professional backgrounds, this volume classifies phenomena not by system but rather by the type of competing interactions involved. This allows for a straightforward presentation of the underlying principles and the universal laws governing the behaviour of different systems. Starting with a historical overview, the author proceeds by describing self-competitions of various types of interactions (such as diploar or multipolar interactions), competitions between a short-range and a long-range interaction (as in Ising systems or DNA models) or between a long-range interaction and an anisotropy (as in ultrathin magnetic films or magnetic nanoparticles) and finally competitions between interactions of the same range (as in spin glasses). Each chapter contains a few problems with solutions which provide suitable material for lecturers of mathematics and physics as well as biology courses. A vast body of references to the original literature make the volume self-contained and ideally suited to master this interdisciplinary field.