The Sun: A Laboratory for Astrophysics presents an educational overview of many aspects of solar physics, in an astrophysical context, following two decades of major strides in solar studies from spacecraft and pioneering studies of the Sun as a star. The authors were chosen for the breadth of their interests, most having experience in both theory and observation, and many in instrumentation. The first third of the book addresses the global physics of the Sun and its relation to other stars, covering energy generation, interior structure models, convection, magnetic field generation, as well as constraints obtained from surface observations, both seismic and magnetic. The second portion comprises a mixture of theory and diagnostics of the solar atmosphere and of instrumentation for observations from radio wavelengths to high energies. The final third concerns solar activity and flares, their relation to stellar activity, and their importance for the activities of humankind.