Concussion - The Hidden Trauma in contact Sports and the NFL - Concussion and mild traumatic brain injury (mTBI) represent a spectrum of neurological injuries that have gained unprecedented attention in recent decades, particularly within the realm of sports medicine. The recognition and understanding of concussion symptoms have evolved dramatically, driven largely by high-profile cases in professional sports, especially the National Football League (NFL), and mounting scientific evidence about the serious nature of these seemingly "mild" injuries. The symptomatology of concussion is complex and multifaceted, encompassing physical, cognitive, emotional, and sleep-related manifestations that can vary significantly between individuals and across different contexts. In sports settings, particularly in contact sports like American football, the presentation and recognition of these symptoms carry unique challenges and implications that extend far beyond the playing field. This book provides a comprehensive examination of concussion symptoms, with particular emphasis on sports-related concussion and the landmark developments in understanding that have emerged from NFL research, policy changes and holistic approach of its management. The evolution of symptom recognition in professional football has not only transformed how we approach sports-related brain injury but has also influenced broader medical understanding of mild traumatic brain injury across all populations.