A church bell is a bell in a church building designed to be heard outside the building. It can be a single bell, or part of a set of bells. Their main function is to call worshippers to the church for a service of worship, but are also rung on special occasions such as a wedding, or a funeral service. In certain Christian traditions, such as Catholicism and Lutheranism, church bells signify to people both inside and outside of the church that a particular part of the service (such as the recitation of the Lord's Prayer or consecration of Holy Communion) has been reached. The ringing of church bells thrice a day occurs in congregations of certain Christian denominations as a call to prayer, reminding the faithful to pray the Lord's Prayer or the Angelus Domini.

The traditional European church bell (see cutaway drawing) used in Christian churches worldwide consists of a cup-shaped metal resonator with a pivoted clapper hanging inside which strikes the sides when the bell is swung. It is hung within a steeple or belltower of a church or religious building, so the sound can reach a wide area. Such bells are either fixed in position ("hung dead") or hung from a pivoted beam (the "headstock") so they can swing to and fro. A rope hangs from a lever or wheel attached to the headstock, and when the bell ringer pulls on the rope the bell swings back and forth and the clapper hits the inside, sounding the bell. Bells that are hung dead are normally sounded by hitting the sound bow with a hammer or occasionally by a rope which pulls the internal clapper against the bell.

A church may have a single bell, or a collection of bells which are tuned to a common scale. They may be stationary and chimed, rung randomly by swinging through a small arc, or swung through a full circle to enable the high degree of control of English change ringing.

Before modern communications, church bells were a common way to call the community together for all purposes, both sacred and secular. In some Christian traditions bell ringing was believed to drive out demons.

Oriental Orthodox Christians, such as Copts and Indians, use a breviary such as the Agpeya and Shehimo to pray the canonical hours seven times a day while facing in the eastward direction; church bells are tolled, especially in monasteries, to mark these seven fixed prayer times.

In Christianity, some churches ring their church bells from belltowers three times a day, at 9 am, noon and 3 pm to summon the Christian faithful to recite the Lord's Prayer; the injunction to pray the Lord's prayer thrice daily was given in Didache 8, 2 f., which, in turn, was influenced by the Jewish practice of praying thrice daily found in the Old Testament, specifically in Psalm 55:17, which suggests "morning and evening plus at noon", and Daniel 6:10, in which the prophet Daniel prays thrice a day. The early Christians thus came to pray the Lord's Prayer at 9 am, noon and 3 pm.

Many Catholic Christian churches ring their bells thrice a day, at 6 am, noon, and 6 pm to call the faithful to recite the Angelus, a prayer recited in honour of the Incarnation of God.

Some Protestant Christian Churches ring church bells during the congregational recitation of the Lord's Prayer, after the sermon, in order to alert those who are unable to be present to "unite themselves in spirit with the congregation".