This volume serves as the primary technical reference for the NeXTSTEP operating system environment, addressing the core question of how developers can effectively interface with its proprietary frameworks and object-oriented architecture. Authored by the engineering team at NeXT Computer Inc., the text provides the foundational documentation required to build applications within the NeXTSTEP ecosystem. It utilizes technical specifications, API definitions, and architectural diagrams to establish a standardized development framework for programmers working on the platform.

Experts and developers of the era identify this as a foundational text for understanding the NeXTSTEP platform's unique design philosophy. Readers frequently note the high density of technical prose and the necessity of this manual for any serious development work on NeXT hardware.