Soy wax made from the soybean plant has become an alternative to paraffin wax. Soy candles burn clean producing 90-95% less soot than paraffin candles and burn cooler resulting in faster scent dispersion. Soy wax is also water soluble making wax spills easier to clean up by using hot soapy water. A candle is a light source usually consisting of an internal wick that rises through the center of a column of solid fuel. Prior to the mid 19th century, the candle was made from tallow (a byproduct of beef fat rendering). The fuel now is nearly always some form of wax, with paraffin wax being the most common. Gel, soy, beeswax, and a vegetable-based candle is also available. A candle manufacturer is usually known as a chandler. Various devices have been invented to secure candles into place, from simple tabletop candle holders, to elaborate chandeliers.

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 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). 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 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, ideally, consumed in the flame, limiting the exposed length of the wick and keeping the temperature and rate of fuel consumption even. Some wicks require manual trimming with scissors or a wick trimmer for even burning.