Spheromaks are easily formed, self-organized magnetized plasma configurations that have intrigued plasma physicists for over two decades. Sometimes called magnetic vortices, magnetic smoke rings, or plasmoids, spheromaks first attracted attention as a possible controlled thermonuclear plasma confinement scheme, but are now known to have many other applications.This book begins with a review of the basic concepts of magnetohydrodynamics and toroidal magnetic configurations, then provides a detailed exposition of the 3D topological concepts underlying spheromak physics, namely magnetic helicity,