[7][8] Falcons are widely distributed on all continents of the world except Antarctica, though closely related raptors did occur there in the Eocene.

[9] Adult falcons have thin, tapered wings, which enable them to fly at high speed and change direction rapidly.

Fledgling falcons, in their first year of flying, have longer flight feathers, which make their configuration more like that of a general-purpose bird such as a broadwing.

As with hawks and owls, falcons exhibit sexual dimorphism, with the females typically larger than the males, thus allowing a wider range of prey species.

[10] As is the case with many birds of prey, falcons have exceptional powers of vision; the visual acuity of one species has been measured at 2.6 times that of human eyes.

[12] The genus Falco was introduced in 1758 by the Swedish naturalist Carl Linnaeus in the tenth edition of his Systema Naturae.

Some sources give the etymology as deriving from the fact that a male falcon is about one-third smaller than a female[18][19][20] (Old French: tiercelet).

The word arose by mistaken division of Old French un niais, from Latin presumed nidiscus (nestling) from nidus (nest).

[24][25] Given the distribution of fossil and living Falco taxa, falcons are probably of North American, African, or possibly Middle Eastern or European origin.

They are, on average, more delicately patterned than the hobbies and, if the hierofalcons are excluded (see below), this group typically contains species with horizontal barring on their undersides.

They represent taxa with, usually, more phaeomelanins, which impart reddish or brown colors, and generally more strongly patterned plumage reminiscent of hawks.

The malar-striped kestrels apparently split from their relatives in the Gelasian, roughly 2.0–2.5 million years ago (Mya), and are seemingly of tropical East African origin.

Some groups of falcons, such as the hierofalcon complex and the peregrine-Barbary superspecies, have only evolved in more recent times; the species of the former seem to be 120,000 years old or so.

[37] The Eocene fossil "Falco" falconellus (or "F." falconella) from Wyoming is a bird of uncertain affiliations, maybe a falconid, maybe not; it certainly does not belong in this genus.