Bell, French cloche, German Glocke, Italian campana, hollow vessel usually of metal, but sometimes of horn, wood, glass, or clay, struck near the rim by an interior clapper or exterior hammer or mallet to produce a ringing sound. Bells may be categorized as idiophones, instruments sounding by the vibration of resonant solid material, and more broadly as percussion instruments. The shape of bells depends on cultural environment, intended use, and material of construction. The walls vary from straight to convex, concave, hemispherical, barrel shaped (as in East Asia), and tulip shaped with sound bow (the bulge near the rim), as are all tower bells in the West. In cross section they may be round, square, rectangular, elliptical, or many-sided. Chinese bells often have lotus-shaped rims.
The strongest sound-producing vibrations of bells occur near the rim (in Western bells, in the sound bow), in contrast to hollow gongs, the vibrations of which are strongest in the centre. The acoustical structure of bell sound is complex and has been completely understood only in modern times. All bells contain an array of partials, or sound-wave frequencies of various pitches, but the tone of a musical bell consists of both harmonious partials and higher inharmonious partials. Western bells are invariably rung by a metal striker; Asian bells, except for metal-clappered hand and wind bells, are normally struck by a wooden hand mallet or swinging horizontal beam that engages the exterior wall. Asian bells are also devoid of the sound bow and never swing.
Bells are widely distributed geographically and usually possess a clearly defined cultural status. Legends surround them, and beliefs abound concerning their special powers—to induce rain or to dissolve storm clouds; to thwart demons when worn as amulets or when placed on animals, buildings, or conveyances; or to invoke curses and lift spells. The concept of their purifying action is ancient, as is their use in ritual, especially in the religions of eastern and southern Asia. The Chinese rang bells to communicate directly with spirits, and in Russian Orthodoxy, bells directly addressed the deity—hence, huge ones were cast by both peoples to lend greater authority. In both Buddhism and Christianity, bells are consecrated before being used liturgically, and in East Asia the fading tone of the bell is considered spiritually significant. In Roman Catholicism, bells have symbolized paradise and the voice of God.