The FIS is based on the patterns formed by the ridges of the inner surface of the bulb on the first joint of the fingers. It is considered simple both in the length of time needed to train individuals in its use and the material needed to utilize the system. The system is positive since it is based on a physical feature of an individual's person which cannot be taken away from him to be used by another. Of the nearly 200 million fingerprint sets on file with the FBI, no 2 individual impressions have ever been found to be identical. The procedures of printing are listed along with equipment needed. An explanation of the classification of prints is presented with emphasis on definition of pattern. The next identifying feature, the ridge count, is discussed and illustrated with pictures. Additional information required when positive identification is not determined is called the fault count. Examples are shown and analyzed. Fingerprint identification messages, a means of converting fingerprint information into a form adaptable to radio transmission, are discussed and shown. 62 figures.