This book introduces the concept of bacterial communication systems from a mathematical modeling point of view. It sheds light on the research undertaken in the last three decades, and the mathematical models that have been proposed to understand the underlying mechanism of such systems. These communication systems are related to quorum sensing mechanisms and quorum sensing regulated processes such as biofilm formation, gene expression, bioluminescence, swarming and virulence. The book further describes the phenomenon of noise, and discusses how noise plays a crucial role in gene expression and the quorum sensing circuit operationusing a set of tools like frequency domain analysis, power spectral density, stochastic simulation