This book aims to popularize physics by emphasizing conceptual ideas of physics and their interconnections, while avoiding mathematics entirely. The approach is to explore intriguing topics by asking and discussing questions, thereby the reader can participate in developing answers, which enables a deeper understanding than is achievable with memorization.The topic of this volume, ‘Colors, light and Optical Illusions’, is chosen because we face colors and light every waking minute of our lives, and we experience optical illusions much more often than we realize.This book will attract all those with a curious mind about nature and with a desire to understand how nature works, especially the younger generation of secondary-school children and their teachers.