Aura pick up vibrational energies that are floating around everywhere you go. Negative emotions of people around you can stick to it.
 
This is a gentle "combing" technique, in which a giant comb made of pure white energy is combed through your aura, gently cleaning out all negativity which sticks to the comb. Once the aura cleansing is complete, a gentle aura revitalization completes the process. 
An aura revitalization will strengthening and fortifying it with pure white energy, making you feel revitalized and energized. 

People often find that this has an extremely positive affect on their health as well, because all negativity is gently lifted away, allowing the aura to do a better job of protecting you from negative energies.