This review is intended as an introduction to mesomagnetism, with an emphasis
on what the defining length scales and their origins are. It includes a brief
introduction to the mathematics of domains and domain walls before examining
the domain patterns and their stability in 1D and 2D confined magnetic
structures. This is followed by an investigation of the effects of size and
temperature on confined magnetic structures. Then, the relationship between
mesomagnetism and the developing field of spin electronics is discussed. In
particular, the various types of magnetoresistance, with an emphasis on
the theory and applications of giant magnetoresistance and tunnelling
magnetoresistance, are studied. Single electronics are briefly examined before
concluding with an outlook on future developments in mesomagnetism.