In this book, the authors gather research from across the globe in the study of the characteristics, composition and orbits of comets. Topics discussed include the role of collisions and magneto-electrochemistry in the planetary origins of comets; 19th century cometary observations; icy particles of cometary atmosphere; cavities as a source of outbursts from comets; infrared observations of comets and the role of comets as contributors to the early evolution of Earth.