candle

A light source typically consisting of a wax cylinder (stearic acid, paraffin wax, etc) with a central fibrous wick, known from ancient times (at least 3000 BC). Light is generated by burning liquid wax melted by the flame and drawn up the wick by capillary action. The International Standard Candle was a measure of light-source intensity, now replaced by the candela.

A candle is a light source usually consisting of an internal wick which rises through the center of a column of solid fuel.

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. 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 liquified fuel then moves upward through the wick via capillary action, and the liquified 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).

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, ideally, consumed in the flame, limiting the exposed length of the wick and keeping the temperature and rate of fuel consumption even.