Tealights are small candles in aluminum containers that usually have a diameter of 39 mm and burn for 3 - 4 hours, as you can read in the surprisingly extensive Wikipedia article on this topic. Especially now in the fall, you can use the little lights to create a cozy atmosphere when baking cookies, or spill the wax and make a mess. Incidentally, the tealight wax liquefies so quickly because the aluminum containers have a very high thermal conductivity.
The romantic embellishment of the living situation with candles can also be used for unplanned bivouacs in snow caves. The tealight is ideal here due to its low weight. You can throw it in your backpack and then never think about it again until it's time to raise the mood and temperature in the snow hole.