A.A. Kirillov's pioneering 1962 paper on nilpotent orbits places him as the founder of orbit theory. The orbit method influenced the development of several areas of mathematics in the second half of the 20th century and continues to be an important tool today. In this volume, prominent contributors present original and expository invited papers in the areas of Lie theory, geometry, algebra, and mathematical physics. An invaluable reference for researchers...