This book proposes a dynamic, neurobiologically grounded theory of concepts. Challenging static, definition-based accounts, it argues that concepts are context-sensitive activation states of neural networks shaped by synaptic plasticity and engram-based memory systems. Drawing on cognitive psychology, and contemporary neuroscience, the book integrates classical debates on conceptual representation with current empirical models of memory, offering a unified framework for understanding how concepts are formed, activated, and used in real time; It also explores the implications of this approach for explaining phenomena such as working memory, intuition, ToT and SoT errors and symbolism.