The investigation of discrete symmetries is a fascinating subject which has been central in the agenda of physics research for 50 years, in several fields, and is the target of many experiments, ongoing and in preparation, all over the world. This book approaches the subject from a somewhat less traditional angle: while being self-contained and suitable to the reader who wants to acquire a solid knowledge of the topic, it puts more emphasis on the experimental aspects of the field, trying to provide a wider picture than usual and to convey the intellectual challenge of experimental physics and the related connection to phenomenology, a purpose for which the precision experiments in this field--often rather elegant and requiring a good amount of ingenuity--are very well suited. Discrete symmetries (parity, charge conjugation, time reversal and of course CP symmetry) in microscopic (atomic, nuclear and particle) physics are discussed, including the detailed description of some key or representative experiments, discussing their principles and challenges more than the historical development. The main past achievements and the most recent developments are both discussed.The level goes from introductory to rather advanced; while mainly addressed to graduate students, the book can also be useful to undergraduates (by skipping some of the most advanced sections and profiting from brief introductions to some topics in the appendixes), and to young researchers looking for a wider modern overview of the issues related to CP symmetry.