Design Patterns: Elements of Reusable Object-Oriented Software

This book, written by the 'Gang of Four' (Erich Gamma, Richard Helm, Ralph Johnson, and John Vlissides), is a comprehensive guide to software design patterns.

It is divided into two parts, with the first part discussing object-oriented design techniques and the second part detailing 23 classic design patterns.

The book includes examples in C++ and Smalltalk and has been highly influential in the field of software engineering, emphasizing principles such as programming to an interface rather than an implementation and favoring object composition over class inheritance.