The mouth, buccal cavity, or oral cavity is the first portion of the alimentary canal that receives food and begins digestion by mechanically breaking up the solid food particles into smaller pieces and mixing them with saliva. The oral mucosa is the mucous membrane epithelium lining the inside of the mouth.
In addition to its primary role as the beginning of the digestive system, in humans the mouth also plays a significant role in communication. While primary aspects of the voice are produced in the throat, the tongue, lips, and jaw are also needed to produce the range of sounds included in human language. Another non-digestive function of the mouth is its role in secondary social and/or sexual activity, such as kissing. The physical appearance of the mouth and lips play a part in defining sexual attractiveness.
The mouth is normally moist, and is lined with a mucous membrane. The lips mark the transition from mucous membrane to skin, which covers most of the body.