This volume serves as the definitive technical reference for the NeXTSTEP development environment and the Objective-C programming language. Authored by the engineering team at NeXT Computer Inc., the text provides the foundational syntax, class hierarchies, and architectural principles required to build applications within the NeXTSTEP operating system. It functions as a primary manual for developers seeking to leverage the object-oriented capabilities of Objective-C in a production environment.

Experts and historians of computing identify this as a foundational text for understanding the evolution of modern macOS and iOS development. Readers frequently note the high level of technical density and the specific historical context required to appreciate the architectural decisions presented in the manual.