This book deals with the behavior of a liquid in zero-gravity or conditions close to it. The surge of interest in zero-gravity problems stems from the progress attained in the field of spaceflight, where such conditions can be attained for long periods of time. Hence the very term "zero-gravity" has a romantic halo about it: although spaceflights have become an accepted fact of life, they are not by any means everyday occurrences. Each new spaceflight involves the best that the present-day level of scientific and technical advancement can offer, and may be considered as a quest for the unknown.