The word aura is often used in a new age way to signify colors surrounding people, animals or even objects. These colors can not be seen, except by certain very gifted people or expensive special photography.
Though, it is true that on a physics level absolutely everything does indeed emanate some level of energy and it is a given that everything that generates warmth like warm blooded creatures will indeed emanate that warmth.

Aura’s can also mean distortions in the sight of people with eye problems. Because of the shape that the distortions take.
When the weather is even the slightest bit misty, you can see an aura around the moon. This aura is not really around the moon but it looks that way. In the literal sense it is an aura.

So far there is not any scientific proof of people who can see or manipulate aura’s. This also means that there is no official license for people claiming this ability. Which means that people can easily lie about having the ability.
Hopefully we will one day find out for once and all what our physical radiations really look like. Till then aura’s seem to be mostly in the minds of the beholder.
Minds who love colorful allegories to describe the abstract into something that is easier to visualize.
Which is why literature loves the figurative use of the word “aura”.

• http://realityshifters.com/pages/auraday.html