Species

A species (plural also species) is a taxonomic unit usually defined to be a set of all individuals of sufficient genetic similarity that they can interbreed and produce fertile offspring. This definition may be supplemented by more careful analysis of DNA similarity, or of similarity of morphology (e.g., comparative anatomy).

A related, but scientifically unfounded idea, used by creationists and based largely on the Bible, is that of kinds.

The term speciation refers to the splitting off of one species from another, a process that has happened countless times in the descent of all known life from a common ancestor over billions of years of evolution. Speciation is an example of so-called macro-evolution, another pseudo-scientific concept used by critics of evolution.