A candle is a light source usually consisting of an internal wick which rises
through the center of a column of solid fuel. Typically the fuel is some form
of wax with paraffin wax being the most common. Prior to the candle being
ignited, the wick is saturated with the fuel in its solid form. The heat of the
match or other flame being used to light the candle first melts and then
vaporizes a small amount of the fuel. Once vaporized, the fuel combines
with oxygen in the atmosphere to form a flame. This flame then provides
sufficient heat to keep the candle burning via a self-sustaining chain of
events: the heat of the flame melts the top of the mass of solid fuel, the
liquefied fuel then moves upward through the wick via capillary action, and
the liquefied fuel is then vaporized to burn within the candle's flame. The
burning of the fuel takes place in several distinct regions (as evidenced by
the various colors that can be seen within the candle's flame). Within the
bluer, hotter regions, hydrogen is being separated from the fuel and
burned to form water vapor. The brighter, yellower part of the flame is the
remaining carbon soot being oxidized to form carbon dioxide.

As the mass of the solid fuel is melted and consumed, the candle grows
shorter. Portions of the wick that are not evaporating the liquid fuel are
themselves consumed in the flame, limiting the exposed length of the wick.

Usage
Prior to the domestication of electricity, candles were a common source of
lighting, before, and later in addition to, the oil lamp. Due to local
availability and the cost of resources, for several centuries up to the 19th
century candles were more common in northern Europe, and olive oil lamps
more common in southern Europe and around the Mediterranean Sea.
Makers of candles were known as chandlers.

Today, candles are usually used for their aesthetic value, particularly to set
a soft, warm, or romantic ambience, and for emergency lighting during
electrical power failures. Scented candles are common in aromatherapy.
Small candles are often placed on birthday cakes.

Religion
Candles are used in religious ceremonies.

Christianity
In Christianity, they typically represent the light of Jesus, and are often
placed on the altar. Votive candles may be lit as an accompaniment to
prayer. Candles are lit by worshippers in front of icons in Orthodox and
other churches.

Candlemas marks the end of the season of Epiphany.
Candles were traditionally used to light up Christmas trees before the
advent of electric lights. They are still, even today, commonly used to
decorate Christmas trees in Denmark and other European countries. They
are also used in Advent wreaths.

In Sweden (and other Scandinavian countries), St. Lucia Day is celebrated
on December 13 with the crowning of a young girl with a ring of candles.

Judaism
In Judaism, candles are traditionally lit on Friday evening at the start of the
weekly Sabbath celebration. The Jewish holiday of Chanukah, also known
as the Festival of Lights, is celebrated by lighting a candle in a special
candelabrum (menorah) each night during the eight-day holiday to
commemorate the dedication of the altar in the Temple in Jerusalem.
Candles are also used in remembering a deceased loved one, especially on
Yom HaShoah, The Day of the Holocaust.

Kwanzaa
Candles are also used in celebrations of Kwanzaa, which is an African
American holiday, which runs from December 26 to January 1.