The aura, in the sense of the spiritual practice, is a field of energy surrounding that is all living and sometimes even in inanimate objects. It can be sensed by the people with delicate senses and sometimes even visually seen by the people with keen senses. Aura basically consists from the life force what every living being emits around them.
For those who can observe it visually, aura is usually shown in different kind of body surrounding colors depending on what kind of energy it's owner emits: This energy may vary depending of his or hers personalities, character, mood or even body health. In some occasions the energy left by the people can be even absorbed into surroundings like to an inanimate objects or places where then this energy can be seen as aura or otherwise sensed.
General fact surrounding this subject is that colors of the aura tend to follow specific situations such as certain colors on certain health or situations. This has enabled healers and witches alike to try to balance or control their own or other people's aura by using same colors as aura has to increase certain color of aura or descrease other aura colors by using opposite colors as in room or area decoration, light, stones, candles or as mostly with candles.
In addition for using colors in the environment or with objects for balancing aura colors, colors or certain colored objects are also used to control chakras - a energy centers of the body which controls different kind of areas in the body. These said energy centers, or energy vortexes around body, have specific kind of colors and by trying to increase or decrease energy output of certain energy vortex using specific colors in candles or stones, healers have healed pains and sicknesses around bodies for centuries.