Lychnomancy is a form of symbolic divination by candle flame, view this great introduction article on lychnomancy. It is a branch of pyromancy (divination by fire), concerned with interpreting the flames of three identical candles arranged in a triangle.
Once a question is asked, the candle flames are used to interpret the answer. If one flame burns brighter than the others, the answer is positive. Wavering flames indicated a journey. If your flame spirals upward, enemies are plotting against you; danger is likewise foretold with an uneven flame. If sparks occur, caution is advised. It is considered very bad luck if all flames are extinguished at once.