The examples and perspective in this article may not represent a worldwide view of the subject. (December 2010)
Altar candles are candles set on or near altars for religious ceremonies. Various denominations have regulations or traditions regarding the number and type of candles used, and when they are lit or extinguished during the services.
Altar candles may sit directly on the altar or be placed in tall stands to the side of or behind the altar. For safety, altar candles are secured in some type of candle holder which may be simple or elaborate. To prevent wax from dripping, candles are often topped by a "candle follower", a short tube made of brass, glass or some other non-flammable material.
In the Roman Rite of the Catholic Church, candles are required to be placed on or beside the altar, at least for the celebration of Mass. For reasons of religious tradition, the Church used the candles at divine service that are made of beeswax.
To the three elements of a lit altar candle, some writers attached a symbolism related to Jesus Christ: the beeswax or other material symbolizing his body, the wick his soul, and the flame his divinity.
Also, the symbolism of prayer has been connected with candles; the burning flame of the candle represents the prayer that rises to God.
For celebration of Mass, it is required that "on or next to the altar are to be placed candlesticks with lighted candles: at least two in any celebration, or even four or six, especially for a Sunday Mass or a holy day of obligation. If the Diocesan Bishop celebrates, then seven candles should be used, except if he is outside the boundary of his jurisdiction".
At the beginning of the 20th century, complex rules governed the composition and number of candles to be used at Mass. Lighted candles of the correct composition (beeswax, with no more than a minimal admixture of other material, and usually bleached) were considered so essential that, if before the consecration they happened to go out (quenched, for instance, by a gust of wind) and could not be relit within fifteen minutes, the celebration of Mass had to be abandoned, and some writers maintained that even if the candles could be relit within that time, Mass should in any case be begun again from the start. Some of these rules were formulated only in the second half of the nineteenth and the beginning of the 20th century. The Roman Missal of the time continued to indicate merely that on the altar there should be "at least two candlesticks with lit candles" with a centrally placed cross between them (Rubricae generales Missalis, XX - De Praeparatione Altaris, et Ornamentorum eius). There is also a rule given in the same section of the Roman Missal - and still included even in the typical 1920 edition - that "a candle to be lit at the elevation of the Sacrament" should be placed with the cruets of wine and water to the Epistle side of the altar.
In the Byzantine Rite, either candles or oil lamps are prescribed for use on the Holy Table (altar). Traditionally, in the Eastern Orthodox Church, only pure beeswax candles may be offered in an Orthodox church. These may be plain or bleached—in some places, bleached beeswax candles are reserved for the Paschal season (Easter).
There will often be a matched pair of candlesticks to either side of the tabernacle, which are lit at any time the Holy Doors in the Iconostasis are opened. In the Slavic practice, these candlesticks usually hold a single large candle; in the Greek practice, these may be five-branch candlesticks. Additionally, there is also a large seven-branch candlestick directly behind the Holy Table.
A Sanctuary lamp (usually oil, but sometimes wax) will also be placed either on the Holy Table, or suspended above it. Traditionally, this lamp should be kept burning perpetually.
Other Christian churches
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The use and regulation of candle use in Lutheran churches vary.
Arthur Carl Piepkorn, in a liturgical directory entitled “The Conduct of the Service,” stated that the normal Lutheran practice was to use two candles on the altar:
It is proper to light the altar candles for all services. The Lutheran use is to have two single beeswax candles, set near the extremities of the altar, either on the gradine or as close as possible to the back of the mensa, if there be no gradine. Six candles is a Counter-Reformatory Roman use. Candelabra as substitutes for the two single candles are a Protestant sentimentality. The Epistle candle is lighted first; the Gospel candle last; they are extinguished in reverse order. Lighting with a match held in the hand is not reverent:—extinguishing with puffs of breath from bloating cheeks is even less so. Use a lighter and snuffer. The lights may be lit by the officiant if there be no one to assist him, or by a choirboy, or by a server appointed for the purpose. In any case the individual performing this task should be decently vested. New candles should be started before the service, or they may cause embarrassing difficulties.
In the traditionally high church Church of Sweden the use of altar candles is meticulously regulated and will, much as the liturgical colour, vary depending on the liturgical year and is listed along with the prescribed altar flowers in its lectionary. With the exception of Good Friday (when at the conclusion of the Maundy Thursday mass the altar has been stripped in a ritual fashion and thus have no candles upon it) it prescribes two candles for the ordinary, four candles for minor feast days and a full six candles for major feast days. 
The use of a row of six candlesticks on the altar, or on a shelf or gradine behind it, is pure Romanism, and a defiance of the Ornaments Rubric, as of all other authority in the Church of England. From the beginning of the thirteenth century to the end of the nineteenth every declaration on the subject has mentioned the two lights on the altar only, and to this ancient and universal use of two lights, at the most, every known representation bears witness. Any one within reach of a large picture-gallery can verify this for himself; in the National Gallery, for instance, there are many illustrations of great interest in the Flemish, German, and Italian rooms and among the drawings of the Arundel collection. The evidence of the inventories, directories, &c., is practically the same. Now the instinct which led the church in the great ages of architecture and craftsmanship to use altar lights in this way was a true one; for an altar with two candlesticks upon it is more majestic and more beautiful than an altar with more than two. Furthermore, a row of candles hides the reredos or upper frontal, which ought to be one of the richest and most lovely things in the church. . . .
He points out, however, that English and north European sanctions the use of other candles near the altar, e.g., there were "very often two Standards on the pavement" and "one very beautiful method was to have sconces for candles on the top of the four poles that sometimes stood at the four corners of the altar to carry the riddels." He concludes:
A church may therefore have (1) two lights on the altar; (2) two standards on the pavement, or four if the sanctuary is large enough (as is seldom the case) for their comely arrangement without overcrowding; (3) other lights near but not behind the altar (preferably two or four on the rods or pillars for the riddels) for use on the principal feasts; (4) others hanging from the roof in candelabra."
In the Protestant Episcopal Church in the United States of America, churches typically use two candles in the following manner:
Altar candles are tall, thin candles made of beeswax and stearine. They are topped with a brass or glass candle follower, which helps keep wax from spilling on the altar linens. Altar candles are lit using a taper, which is a lit wick attached to a long handle. They are lit and extinguished in a particular order so that the Gospel side candle is never burning alone. The Gospel side of the church is the left side as you are facing the front. So the candles are lit from right to left and extinguished from left to right. 
In the mainline Presbyterian and denominations such as the PCUSA and the PCA it is common to see two candles on the Communion table in front of the chancel. It is also common to see 7 candle candelabras on each side of the Communion table as well. You may also see Candles lights on the pavement on each side of the sanctuary. These can also be seen in other Reformed churches such as the Reformed Church in America and in the United Church of Christ (UCC) Please note St Giles Cathedral below ( Church of Scotland) is the mother church for the Presbyterian Church USA. Typically mainline Presbyterian churches in America have been following the placing of candles since the 19th century in a similar manner to the Anglican tradition.
https://cathedralofhope.org/worship/stream-services/ https://www.shadysidepres.org/worship/worship-archive/ https://ststephenpresbyterian.com/worship/choral-evensong/ https://www.presbyterianmission.org/ministries/worship/faq/faq-signssymbols/ https://stgilescathedral.org.uk/remembrance-sunday-1130am/
Methodist churches typically use (normally two) candles in a manner similar to the Anglican way.
Many congregations use two candles on the altar to point out that Jesus was both a human being and God. At the end of the service, the light is carried out into the world to show that Jesus Christ is for all people everywhere…The acolyte leaves the worship service at the pastor’s direction, carrying out the lighted candlelighter. This symbolizes the light of Jesus Christ going out into the world where believers are to serve.
- "Catholic Encyclopedia". New Advent.
- "Celebrating the Different Forms of Mass – Mass with a Congregation (article 117)". General Instruction of the Roman Missal (PDF). Catholic Truth Society. April 2005. ISBN 1-86082-288-6. Archived from the original (PDF) on 6 February 2007. Retrieved 2007-02-13.
- Schulte, A.J. (1907). "Altar Candles". The Catholic Encyclopedia. 1. New York: Robert Appleton Company. Archived from the original on 13 February 2007. Retrieved 2007-02-13.
- "Missale Romanum" (PDF). 1920-07-25. Archived (PDF) from the original on 2006-11-05. Retrieved 2007-02-13.
- The Rev. Dr. Arthur Carl Piepkorn, “The Conduct of the Service,” Archived 2009-05-28 at the Wayback Machine CSPS 1965 (Revised Edition)
- "Kyrkoårets bibeltexter".
- Percy Dearmer, The Parson's Handbook (1907 ed.), pp. 96–97.
- Percy Dearmer, The Parson's Handbook (1907 ed.), p. 99.
- Percy Dearmer, The Parson's Handbook (1907 ed.), p. 100.
- "The Lighting of the Altar Candles for Episcopalians | Synonym". classroom.synonym.com. Retrieved 2021-03-16.
- E. Byron Anderson, ed. (1999). Worship matters : a United Methodist guide to ways to worship. Nashville, Tenn.: Discipleship Resources. ISBN 978-0881772807.
- "What Are the Elements of a Taoist Altar?".