[1] More than 3500 species of skippers are recognized, and they occur worldwide, but with the greatest diversity in the Neotropical regions of Central and South America.

The third and rather small butterfly superfamily is the moth-butterflies (Hedyloidea), which are restricted to the Neotropics, but recent phylogenetic analyses suggest the traditional Papilionoidea are paraphyletic, thus the subfamilies should be reorganized to reflect true cladistic relationships.

Skippers also have generally stockier bodies and larger compound eyes than the other two groups, with stronger wing muscles in the plump thorax, in this resembling many moths more than the other two butterfly lineages do.

For example, some species in the genera Amblyscirtes, Erynnis (duskywings), and Hesperia (branded skippers) cannot currently be distinguished in the field even by experts.

The only reliable method of telling them apart involves dissection and microscopic examination of the genitalia, which have characteristic structures that prevent mating except between conspecifics.