This is the third edition of the Howard and Moore checklist, which was first published as a compact list of the birds of the world and included all subspecies. This third edition has had the input of five regional consultants who have assisted with a reassessment of all taxonomic data. In addition, the authorities for all newly described subspecies are given with full references. Introductory sections include a discussion of the relative attributes of the Biological Species Concept and the Phylogenetic Species Concept, which cause much confusion among birders but which are critical to our understanding of taxonomy and related issues, not least conservation. Additionally, new developments in taxonomy are discussed, and areas highlighted where it appears that a new consensus is likely to emerge in the future.