Corresponding with seven chakras, there are seven layers of human aura, namely, divine body, spiritual body, casual body, mental body, emotional astral body, etheric body and physical auric body. These layers are also called human aura energy fields. Each field has its own color, yet there is an overall color of the aura.
Protecting the Aura
One might be exposed to negative energies anywhere but the chances of exposure become far too great when you move around in public places. There we come across people with varying levels of energies particularly in public places like airports, markets, railway stations etc. and even in the offices. Some of the persons there could possibly have strong negative energy that could affect us in some way if we come close to them. Since it is nearly impossible to identify such energies instantaneously in advance and avoid them, it is better to stay protected. You should therefore, learn to protect your aura. There are several techniques to do so, which your Reiki teacher will teach you during Reiki training class. It hardly takes few minutes to do so or even few seconds once you have practiced enough. This however, does not give protection against physical phenomenon like hitting your knee against a table or physical attack etc. There are other aspects too, which your Reiki teacher will teach you. Remind him in case he forgets. I teach this to my students during their Second Degree Reiki training with me.