A crane fly is any member of the dipteran superfamily Tipuloidea, which contains the living families Cylindrotomidae, Limoniidae, Pediciidae and Tipulidae, as well as several extinct families. "Winter crane flies", members of the family Trichoceridae, are sufficiently different from the typical crane flies of Tipuloidea to be excluded from the superfamily Tipuloidea, and are placed as their sister group within Tipulomorpha.

Flies are insects of the order Diptera, the name being derived from the Greek δι- di- "two", and πτερόν pteron "wing". Insects of this order use only a single pair of wings to fly, the hindwings having evolved into advanced mechanosensory organs known as halteres, which act as high-speed sensors of rotational movement and allow dipterans to perform advanced aerobatics. Diptera is a large order containing an estimated 1,000,000 species including horse-flies, crane flies, hoverflies, mosquitoes and others, although only about 125,000 species have been described.