Species

Species, as a concept used in the Wake of Eärendil universe, refers to (usually sophont) populations that are unable to fertilely interbreed(without intervention of advanced technology or magic). This concept comes from your Earthly World's science of zoology(distinct from botany's different definition of species), and is equivalent to the concept of "race" in many fantasy and even science fiction worlds. Races however are a different, much more socially constructed concept.

Notable species and their worlds
Here are some notable sophont species that inhabit the multiverse of the Wake of Eärendil.