This comprehensive three-volume set investigates the taxonomic classification, evolutionary history, and physical characteristics of every recognized bird family on Earth. Compiled by experts at Oxford University Press, the work synthesizes decades of ornithological research to provide a definitive reference framework for avian diversity. It serves as a primary resource for understanding the global distribution and morphological variations across the class Aves.

Ornithologists and academic researchers frequently cite this set as a foundational reference for avian taxonomy and biodiversity studies. The prose is dense and technical, intended primarily for professional biologists and serious students of natural history.