Candles have been used in ritual work as well as focal points and concentration aids for centuries. Each different color has a different meaning for both internal and external uses.
Here are a list of uses, from Charles Butler:
OUTER WORKS INNER WORKS
RED Energy Courage
ORANGE Generosity Plenty
YELLOW The Unknown Centering
GREEN Prosperity Healing
BLUE Love Emotions
PURPLE Inspiration Spirit
PINK Revelation Joy
BURGUNDY Passion Rekindling
BLACK Comfort Authority
WHITE Vision Protection
