Hares and jackrabbits are leporids belonging to the genus Lepus. A hare less than one year old is called a leveret. Four species commonly known as types of hare are classified outside of Lepus: the hispid hare (Caprolagus hispidus), and three species known as red rock hares (Pronolagus spp.).

Hares are very fast-moving animals; the European brown hare (Lepus europaeus) is able to run at speeds of up to 56 km/h (35 mph). The five species of jackrabbit found in central and western North America are able to run at 64 km/h (40 mph), and can leap up to 3m (ten feet) at a time. They live solitarily or in pairs, while a "drove" is the collective noun for a group of hares.

A common type of hare in Arctic North America is the snowshoe hare, replaced farther south by the black-tailed jackrabbit, white-tailed jackrabbit, and other species.

Normally a shy animal, the European brown hare changes its behavior in spring, when hares can be seen in broad daylight chasing one another around meadows; this appears to be competition between males to attain dominance (and hence more access to breeding females). During this spring frenzy, hares can be seen "boxing"; one hare striking another with its paws (probably the origin of the term "mad as a March hare"). For a long time, this had been thought to be intermale competition, but closer observation has revealed it is usually a female hitting a male to prevent copulation.