A hobby is a fairly small, very swift falcon with long, narrow wings.

There are four birds called "hobby", and some others which, although termed "falcon", are very similar.

The typical hobbies are traditionally considered a subgenus, Hypotriorchis, due to their similar morphology; they have ample amounts of dark slaty grey in their plumage; the malar area is black; and the underside usually has lengthwise black streaks.

[1] Monophyly of Hypotriorchis is supported by DNA sequence data, though the exact limits of the group are still uncertain.

The hobbies seem to be one of the Falco lineages which emerged around the Miocene-Pliocene boundary some 8-5 million years ago and subsequently radiated - in this case throughout the Old World.