This text covers basic classical optics--geometrical and physical--at a level suitable for first or second year undergraduates. The introductory chapter discusses the properties of electromagnetic waves in the optical region and compares them with other regions of the spectrum. The following chapters deal with the geometrical optics model, the propagation of waves, polarization, image formation, and optical instruments. The final chapters on laser light and optical fibers show the applications of ideas developed earlier in the book. For the new third edition, the author has updated the existing text and added a chapter on the detection of light. The book aims to show how the properties of light relate to the rest of physics, and how these properties are used in many of the instruments that are among the basic tools of modern science.