Without signals, trains cannot operate. They indicate, similar to traffic lights on the road, whether and at what speed sections of track may be traversed. There are various types of signals, which can be broadly categorized into main signals, distant signals, and additional signals. This book presents all the important signals in railway traffic and explains their significance. This revised and expanded new edition not only covers some special signals used by private railways but also includes a section on the new, signal-less ECTS system that will control rail traffic in the future.