Telemetry is a technology that allows the remote measurement and reporting of information of interest to the system designer or operator. Telemetry typically refers to wireless communications, but can also refer to data transferred over other media, such as a telephone or computer network or via an optical link. This book provides a brief overview of the telemetric technique and how it has evolved over the years as well as its numerous applications. By providing the geographical location of animals, and sometimes concurrently allowing the registration of other parameters (e.g. activity, temperature), this technique is often used to study home-range size and shape, habitat selection etc. Medical telemetry may be defined as "the measurement and recording of physiological parameters and other patient-related information via radiated bi- or unidirectional electromagnetic signals." This book discusses the telemetric devices that can be coupled with biosensors and micro sensors that generate electrical signals related to electrochemical processes. The engagement of fisheries and polar biologists in acoustic telemetry studies on inshore polar fish is explored by sharing their experiences of the issues surrounding environmental constraint, equipment limitations, tracking protocols, choice of species, and safety in the field. Different steps taken for the telemetric system to record the electroencephalogram (EEG) from adult freely moving rats are described. This novel telemetric system was also used to record brain activity in small animals. The development of a cost-effective telemetric system is addressed, through a combination of a wireless microphone for signal transmission and a computer sound card for recording of signals in the audible range. Finally, the telemetry of body temperature for long-term recordings of breathing is described.