The holiday is a festival of light, reflecting the lengthening of the day and the hope of spring. It is traditional to light all the lamps of the house for a few minutes on Imbolc, and rituals often involve a great deal of candles.
Modern Pagans argue that the Christian feast of Candlemas was a christianisation of the feast of Imbolc. However, the evidence that Imbolc was widely celebrated in pre-Christian times or in relevant places is weak (all accounts of it refer only to Ireland, whereas the celebration of Candlemas began in the Mediterranean region). In North America, Candlemas became known as Groundhog Day.
See also Wheel of the Year.