Over the past hundred years, the Heisenberg group has been recognized as an important object in several areas of mathematics, including group representation theory, mathematical physics, complex analysis in several variables, partial differential equations, and differential geometry. This book presents a concise and readable introduction to all these aspects, together with brief descriptions of further research in the area over the past few decades. The author also provides copious references. Prerequisites for the potential reader are a graduate-level course in modern real analysis, plus the rudiments of functional analysis, Fourier analysis, differential geometry, and Lie groups.