This book consists of a description of 22 classic design patterns first discovered by the "Gang of Four" (or simply GoF) in 1994. Each chapter of the book is devoted to only one pattern. Therefore, the book can be read either sequentially, from edge to edge, or in random order, choosing only patterns that are interesting at the moment. Many of the patterns are interconnected, so you can easily jump into related topics using the links that are provided in abundance in the book. At the end of each chapter, the relationship of the current pattern with the others is given. If you see there the name of a pattern that you haven’t gotten to yet, then simply read on - this point will be repeated in another chapter.