Magnetic Fields in the Early Universe -- Magnetic Fields in Galaxy Systems, Clusters and Beyond -- Magnetic Fields in Galaxies -- The Origin of Galactic Magnetic Fields -- Magnetic Fields in the Milky Way, Derived from Radio Continuum Observations and Faraday Rotation Studies -- Mesoscale Magnetic Structures in Spiral Galaxies -- Magnetic Fields in Diffuse HI and Molecular Clouds -- Stellar Magnetic Fields -- Importance of Magnetic Helicity in Dynamos -- Numerical Magnetohydrodynamics in Astrophysics.While magnetic fields permeate the universe on all scales, the present book is dedicated to their investigation on the largest scales and affords a balanced account of both theoretical and observational aspects. Written as a set of advanced lectures and tutorial reviews, which lead up to the forefront of research, this book offers both a modern source of reference for the experienced researchers as well as a high-level introductory text for postgraduate students and nonspecialist researchers working in related areas.