A candle is a source of light, and sometimes a source of heat, consisting of a solid block of fuel (commonly wax) and an embedded wick. Most candles are cylindrically shaped because they burn best that way, although for decorative purposes candles can have other shapes as well, such as rectangular or heart-shaped.
A special type of candle is the tealight. It is different from a regular candle in that it is a very short stump encased in a thin metal cover. Its wax liquefies completely while lit. The metal cover will get very hot when the tealight burns down, reaching temperatures exceeding 300 Celsius, which is why tealights should only be burnt in a suitable holder or on a surface that can withstand these temperatures.
Candles in BDSM
Candles can also have an appeal due to religious connotations: they can create a solemn, ceremonial atmosphere.
Second, to be used in wax play.