This is a book on Carbyne and Carbynoid Structures - one of the most fascinating and controversial areas in contemporary science of carbon, chemistry, and materials science. The book is a collection of topical and mostly critical reviews written by professionals who are working or have been working in this and related fields. Regretfully, too many ambiguous experimental results and unsubstantiated statements regarding linear carbon allotropes have been published so far in the literature and, therefore, the concept of one-dimensional carbon has encountered harsh criticism among some scientists. The book is certainly not intended to reveal completely new and stunning results on carbyne but rather to provide a complete, ordered and concise summary of what is known (or not known) at this date. The authors have tried to be critical of overstated results and expectations and have made an effort to provide a balanced approach to the controversial topic. The book provides a state-of-the-art standard work on this elusive carbon allotrope. It shows the scientific community clearly what has been confirmed, what is still doubtful, what is/was wrong, and, most importantly, the course for future endeavours. This is the real value of this, the only book in the field, and an internationally balanced roster of contributors appears to succeed in reaching this goal. This book will be of interest to research scientists (both experimentalists and theoreticians), post-graduate and graduate students working in the field of chemistry and physics of carbon (including diamond and diamond-like materials, graphite intercalation compounds, fullerenes, carbon nanotubes and related areas), conjugated and/or bio-polymers, and one-dimensional molecular systems.