Working memory is often described as the "mental workspace" of the human brain. It is the essential ability that allows us to hold, update, and manipulate information in real-time, serving as the bridge between raw perception and purposeful action. Without it, we could not follow a conversation, solve a complex problem, or plan for the future. This volume provides an authoritative and integrative account of this fundamental cognitive system, offering a definitive roadmap of how it works, how it breaks down, and how it can be improved. Organized into five core pillars that move seamlessly from the microscopic to the global, Working Memory begins by exploring the biological foundations of the brain, detailing how chemical signals, hormones, and neural circuits interact to create a stable yet flexible mental environment. It then moves beyond biology to synthesize the latest research on how working memory interacts with other vital functions — such as attention, long-term memory, emotion, and decision-making — to guide our everyday behavior. In addition to explaining the architecture of the healthy mind, this volume takes a deep dive into the human lifespan to explore how working memory develops in childhood, how it shifts during the aging process, and how it responds to injury. It looks toward the future, evaluating emerging interventions such as brain stimulation, technology-driven training, and new biomarkers that promise to enhance our cognitive potential. By unifying diverse perspectives — from molecular biology to large-scale brain networks — Working Memory offers a comprehensive framework for understanding the system that makes adaptive human intelligence possible. It is an essential resource for researchers and an illuminating guide for anyone interested in the inner workings of the human mind.