The synapse is a fascinating structure for many reasons. Biologically, it is an exquisitely organized subcellular compartment that has a remarkable capacity for fidelity and endurance. Computationally, synapses play a central role in signal transmission and processing that represent evolution’s solution to learning and memory. Nervous systems, including our own brains, possess an extraordinary capacity for adaptation and memory because the synapse, not the neuron, constitutes the basic unit for information storage. Because the molecular complexities underlying signal processing and information storage must occur within the tiny space of the synapse, the precise molecular organization of proteins, lipids, and membranes at the synapse is paramount. Given the central role of the synapse in neuronal communication, it comes as no surprise that dysregulation of the synapse accounts for many, if not most, neurological and psychiatric disorders. Clinically, the synapse thus constitutes a primetarget for treatments of these diseases. It is for these reasons that we have chosen to focus our work on deciphering the structural and functional organization of the synapse. We have assembled leaders in the field of synapse biology to describe and distill the wonders and mysteries of the synapse. This book provides a fundamental description of the synapse developed over many decades by numerous investigators, paired with recent insight into new aspects of synapse structure and function that is still in flux and at the cutting edge of research.