This book provides a statistical framework for performance modeling and design of backscatter Radio Frequency Identification (RFID) systems. The current models for estimating performance are based purely on EM theory (e.g., using Friis free space equations) or statistical experimental modeling principles. Models based on EM theory are limited to specifying power received at the tag under certain simple, idealized conditions, and do not provide estimates of read-rates, which are de-facto industry quantifiers of an RFID system performance. On the other hand, the statistical models, being purely data-driven, suffer from lack of generalizability as their results cannot be extrapolated. This book investigates a statistical approach for assessing the system performance and proposes an analytical probabilistic model based on Friis free space expression that captures the uncertainties existing in gain of tag antenna, power of reader antenna, etc. Finally the book suggests a set of techniques to increase read-rate probabilities of RFID tags in the presence of highly metallic environments.