An Aura is an optical effect wherein gas or dust surrounding an object luminesces or reflects light from the object.
The visual disturbance seen by approximately 50% of migraine sufferers is also called aura.
Some people believe that there is a visible energy field, called an aura, that can be seen or otherwise sensed around living beings--especially around humans. These energy fields are sometimes claimed to be documented by a rare form of photography called Kirlian photography. However, these claims are vigorously denied by skeptics about paranormal activity. James Randi, for example, has for many years (as of 2003) offered one million US dollars to any person capable of repeatedly detecting auras, and no person has ever stepped forward to claim the prize. The test involves a simple task.
Figuratively, an aura refers to the character of concepts/issues/phenomena surrounding a particular topic. eg: 'The discussion had an aura of casualness'.
The Marxist cultural critic Walter Benjamin also used the term 'aura' to refer to the feeling of awe created by unique or remarkable objects such as works of art or relics of the past. According to Benjamin older cultures can generate auras around particular objects of veneration, while capitalist culture has the opposite effect, causing the decay of the aura due to the proliferation of mass producion and reproduction technologies.