The term peafowl refers to Gallinaceous Birds classified within the genera Rheinardia, Argusianus, Afropavo,and Pavo.Formerly classified as members of the Phasianidae, it is now well-established that the Phasianidae are not not monophyletic. Peafowl and their allies are a very ancient isolated group with no near allies.

Peafowl are large birds with long necks and legs, heavy squarish wings and elongated tails. adult males of most genera can be distinguished from females due to the presence of extremely elongated and highly specialized dorsal plumage. Adult males of the two species of Great Argus exhibit highly specialized wing coverts which give them the largest wing surface area of any living bird. The Great Argus male's wing is shaped rather like a moth's and is patterned very much like a python. Some native cultures in Burma and Thailand refer to the Great Argus as "Python Moth Bird" for this reason. The Great Argus male also exhibit extremely elongated retrice plumes which are twisted at their ends. Each of the two central retrices resemble snake heads in silhouette, a phenomenon best appreciated in shadows cast by the tail when the birds stand in stationary alert posture. When in this postyre, the tail is held high , in a carriage not unlike a bantam rooster's. The elongated retrices jut out and the bird raises them as if to broadcast the presence of the two feathered "heads". The female Great Argus is essenitally similar to the male but smaller and brighter in colour and without the greatly elongated wing and tail plumage. The female Great Argus also exhibits much more feathering along the nape and occipital ridge.

Males of the two species of Crested Argus lack the greatly elongated wing coverts of their cousins the Great Argus but their wings are very large for the size of the body of the birds. Adult male Crested Argus also exhibit enormous tail feathers just as long as the Great Argus but at least two times as wide. The entire tail is elongated versus only the central retrices. Like the Great Argus, the Crested Argus Male is most striking in prolonged flight. Crested Argus fly in pairs and also with their juvenile offspring in the manner of typical Peafowl. Great Argus may also fly in pairs as well. Great Argus exhibit complex flight displays which the female participates in. Congo Peafowl and Green Peafowls also exhibit flight displays though the Indian Peafowl's flight display are evidentially reduced to stereotypical jumps and glides.

Peafowl differ from most other gallinaceous birds in their habit of gathering on emergent trees well above the canopy in primeval forest habitats or on tall singular trees towering over tropical grassland habitat. Their incubation periods are comparatively long - from 28-34 days. Like other, large bodied primitive Gallinates like the distantly related Megapodes and Cracides, all extent members of the monophyletic Peafowl family are capable of making sustained flights of several yards within a few days. They are born with perfectly formed flight feathers. Junglefowl, Francolins, Partridges, Quail, Pheasants and Grouses develop their wing feathers later than peafowl and are not capable of sustained flight until they at least one week old. Monals and Tragopans are born with developed flight feathers and they too can sustain themselves in flight before they are one week old. Peafowl also exhibit unique leg, tail and breast musculature that distinguishes them from other Gallinates. Their hind toes are also longer than other Old World Gallinates except for members of the Genus Polyplectron which are believed to be distantly related.