This book collects multidisciplinary chapters on the most important problems that arise at mid-ocean ridges. The mid-ocean ridge system is the longest continuous feature of the earth's surface. It is where the great majority of ocean floor is created and volumes of seafloor volcanism vastly exceed those on land. It provides the means for much of the heat loss from the interior of the earth. Chemicals as well as heat are extracted by flowing seawater through the rocks of the seafloor, leading to spectacular areas of hydrothermal venting, that affect ocean chemistry and global climate. The chapters range from studies of the mantle and magma generation within it, through tectonics of mid-ocean ridges, to the physical, chemical and biological dynamics of hydrothermal systems. The book will be of importance to specialists and researchers wishing to become informed of the latest developments in the science of mid-ocean ridges. It will prove especially useful for new scientists entering the field.