White matter is the component of the central nervous system charged with propagating the electrical signals of neurons. It is comprised of axons and glial cells, including oligodendrocytes which wrap the axons in lipid rich myelin, giving the tissue the characteristic appearance after which it is named. Understanding the physiology of white matter in health and the pathophysiology that contributes to numerous diseases is a major focus of neuroscience. This book comprises a collection of works on topics pertinent to the study of white matter, ranging from the basic organisation of the tissue to the study of white matter in disease and as a result will be of interest to those working in both basic and clinical science.