Treeswifts are in the order Apodiformes. There are three families within this order: Hemiprocnidae (treeswifts), Apodidae (true swifts) and Trochilidae (hummingbirds). Treeswifts also belong to the suborder Apodi. There is one genus of treeswifts and 4 species. The four species are: grey-rumped treeswift (Hemiprocne longipennis), crested treeswift (Hemiprocne coronata), whiskered treeswift (Hemiprocne comata) and moustached treeswift (Hemiprocne mystacea).

Treeswifts are insectivores and catch the majority of their prey while flying. Unlike their close relatives, true swifts, treeswifts are able to perch, are not very social and have more ornate coloring (some species have bold white striping on their heads). Treeswifts also have crests on their heads and are easy to identify when perched because of their long crossed wing-tips and deeply forked tail.

They are monogamous and both males and females provide parental care. In-flight copulation has been recorded. Although they occur throughout much of the Oriental region, little is known about the Hemiprocnidae family.