What is fragrance oil

How do you use it?
What is it?

From what I know its oil you put in these things with candles under them and the oil evaporates leaving the fragrance.

It is oil you use as incense. You can put it in warmers that disperse the scent in a room, Candles, soaps...it's nice stuff.

I personally don't use it, but this is what it is:
Fragrance oil(s), also known as aroma oils, aromatic oils, and flavor oils, are blended synthetic aroma compounds or natural essential oils that are diluted with a carrier like propylene glycol, vegetable oil, or mineral oil. Aromatic oils are used in perfumery, cosmetics, flavoring of food, and in aromatherapy.

To some people, synthetic fragrance oils are less desirable than plant-derived essential oils as components of perfume.

You can use oils a lot of ways but I like to put a little on my wrist (like you do at a dept. store but don't use much) and get a whiff once in a while. I love Clarey sage.