A tealight or nightlight, is a candle

Candle

A candle is a solid block or cylinder of wax with an embedded wick, which is lit to provide light, and sometimes heat.Today, most candles are made from paraffin. Candles can also be made from beeswax, soy, other plant waxes, and tallow...

 encased in a thin metal or plastic cover so that the candle can liquefy completely while lit. They are typically small, circular, wider than their height and inexpensive. Because of their small size and low level of light, multiple tealights are often burned simultaneously.

Tealights, in addition to being used as Votive candles, are often used to heat fondue

Fondue

Fondue is a Swiss dish of melted cheese served in a communal pot over a spirit lamp , and eaten by dipping long-stemmed forks with bread into the cheese...

 and as food warmers. They are also suitable for accent lighting and for heating scented oil

Fragrance oil

Fragrance oil, also known as aroma oils, aromatic oils, and flavor oils, are blended synthetic aroma compounds or natural essential oils that are diluted with a carrier like propylene glycol, vegetable oil, or mineral oil...

. Tealights are sometimes floated in water, for decorative effect.

Tealights may be distinguished from nightlights by the duration of burning: a tealight usually burns for 3 to 5 hours but a nightlight, which is larger, is intended to burn for a whole night (about 8 to 10 hours).

Varieties

Tealights can come in many different shapes and sizes, small and large, as well as burn times and scents. However, a common type of tea-light is circular, approximately 38mm diameter by 16mm high, with white unscented wax.

Cup design

The wick

Candle wick

A candle wick is a string, cord, or wooden object that holds the flame of a candle. A candle wick works by capillary action, drawing the fuel to the flame. When the liquid fuel, typically melted candle wax, reaches the flame it then vaporizes and combusts. The candle wick influences how the...

 is tethered to a piece of metal to stop it from floating to the top of the molten wax and burning out before the wax does.

Tealights have been protected under several patented designs. In some cases, the standard tea light metal cup has been replaced with a clear plastic cup. However, the metal cups are still offered by many candle makers. The clear cup allows more light to escape the holder, and even offers a "stained glass" look when multiple colors are used. In the early 2000s, a new shape of cup was patented to encourage more even burning and complete liquefaction

Liquefaction

Liquefaction may refer to:* Liquefaction, the general process of becoming liquid* Soil liquefaction, the process by which sediments become suspended* Liquefaction of gases in physics, chemistry, and thermal engineering* Liquefactive necrosis in pathology...

 of the wax.

Holders

Tealights are especially popular for use with candle holders. From small pockets of glass

Glass

Glass is an amorphous solid material. Glasses are typically brittle and optically transparent.The most familiar type of glass, used for centuries in windows and drinking vessels, is soda-lime glass, composed of about 75% silica plus Na2O, CaO, and several minor additives...

, metal

Metal

A metal , is an element, compound, or alloy that is a good conductor of both electricity and heat. Metals are usually malleable and shiny, that is they reflect most of incident light...

, ceramic

Ceramic

A ceramic is an inorganic, nonmetallic solid prepared by the action of heat and subsequent cooling. Ceramic materials may have a crystalline or partly crystalline structure, or may be amorphous...

 and other materials to larger, more elaborate tea light lamps, holders come in a wide range of styles, colours, and shapes. Holders have an appropriately sized cup to use a tealight candle, either scented or unscented. Discount stores, gift stores, and home decor stores often carry an array of holders for these small candles.