A cockatoo is any of about 20 species of bird belonging to the family Cacatuidae. Along with the Psittacidae family ("true" parrots), they make up the order Psittaciformes (all parrots). The name cockatoo originated from the Malay language 'kakaktua' meaning 'older sister' ('kakak' - sister and 'tua' - old).

Cockatoos share many features with other parrots including the characteristic curved beak shape and a zygodactyl foot (two toes forward and two toes back). They differ however in a number of anatomical characteristics, including the often spectacular movable headcrest, and their lack of the Dyck texture feather composition which gives many parrots their iridescent colours. Cockatoo species are on average larger than other parrot species. The Cockatiel though is a small cockatoo and the very biggest parrots are not cockatoos, the Hyacinth Macaw being the longest and the Kakapo the heaviest.

Cockatoos as a family have a much more restricted range than the larger parrot group, occurring naturally only in Australia and nearby islands.

ORDER PSITTACIFORMES

• Family Cacatuidae
  • Subfamily Microglossinae
    • Palm Cockatoo, Probosciger aterrimus
  • Subfamily Calyptorhynchinae
    • Red-tailed Black Cockatoo, Calyptorhynchus banksii
    • Glossy Black Cockatoo, Calyptorhyncus lathami
    • Yellow-tailed Black Cockatoo, Calyptorhyncus funereus
    • Short-billed Black Cockatoo, Calyptorhyncus latirostris
    • Long-billed Black Cockatoo, Calyptorhyncus baudinii
  • Subfamily Cacatuinae
    • Gang-gang Cockatoo, Callocephalon fimbriatum
    • Galah, Eolophus roseicapilla
    • Long-billed Corella, Cacatua tenuirostris
    • Western Corella, Cacatua pastinator
    • Little Corella, Cacatua sanguinea
    • Major Mitchell's Cockatoo, Cacatua leadbeateri
    • Sulphur-crested Cockatoo, Cacatua galerita
    • Lesser Sulphur-crested Cockatoo, Cacatua sulphurea
      • Citron-crested Cockatoo, Cacatua sulphurea citroncristata
    • Blue-eyed Cockatoo, Cacatua ophthalmica
    • Moluccan Cockatoo or Salmon-crested Cockatoo, Cacatua moluccensis
    • Umbrella Cockatoo, Cacatua alba
    • Red-vented Cockatoo, Cacatua haematuropygia
    • Goffin's Cockatoo, Cacatua goffini
    • Ducorp's Cockatoo, Cacatua ducorpsii
  • Subfamily Nymphicinae
    • Cockatiel, Nymphicus hollandicus
• Family Psittacidae ("true" parrots, over 330 species)