The lion is a species in the family 'Felidae'; it is a muscular, deep-chested cat with a short, rounded head, a reduced neck and round ears, and a hairy tuft at the end of its tail.

Lions have an array of facial expressions and body postures that serve as visual gestures. A common facial expression is the 'grimace face' or flehmen response, which a lion makes when sniffing chemical signals and involves an open mouth with bared teeth, raised muzzle, wrinkled nose closed eyes and relaxed ears.

The repertoire of vocalisations is also large; rather than discrete signals, variations in intensity and pitch appear to be central to communication. Most lion vocalisations are variations of growling, snarling, miaowing and roaring. Other sounds produced include purring, puffing, bleating and humming. Lions tend to roar in a very characteristic manner starting with a few deep, long roars that subside into a series of shorter ones. The sound, which can be heard from a distance of 8 kilometres (5.0 mi), is used to advertise the animal's presence.

Lions usually roar between dusk and dawn. They roar to stay in touch with companions and to advertise their location and strength to rivals. Lions are sensitive to numbers, so they are able to discriminate the roars of large groups from those of small groups. They can also distinguish the roars of companions from those of strangers.

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