Motivated by observation about the imbedding of minimal surfaces by harmonic maps, the author works toward a fundamental problem in harmonic map theory: the classification of maps. The main objective of these notes is to study the parameter spaces of eigenmaps, called moduli spaces. The author presents results on the fine structure of the boundary of these spaces and includes the minimal immersions whose moduli spaces were studied in the pioneering work of DoCarmo and Wallach. As a byproduct he obtains a classification theory for orthogonal multiplications, which are intimately related to Clifford modules. --- from book's back cover