The document discusses biodiversity and taxonomy. It defines a species as a group of organisms that share genes and lineage, and are adapted to particular environmental resources. There are millions of species, many not yet identified. Taxonomy is the science of classifying species in a hierarchical system, from broad kingdoms to specific genera and species, to indicate natural relationships. This ordering system, developed by Linnaeus, helps organize the vast number of species and provides a standardized naming convention. The document also discusses how biodiversity supports ecosystem functions and is declining due to human-caused extinction rates being much higher than background rates.