Perfumers often use vanilla in exotic fragrances because it mixes so well with spicy scents. Like jasmine, vanilla grows on a vine that produces white flowers. However, it's the beans, or the fruit of those flowers, that contains the vanilla. But the beans are costly and cumbersome to harvest and prepare, which is why vanilla is one of the most expensive spices in the world.
Luckily, vanilla extract -- which is often derived in part from lower-grade varieties of vanilla beans -- is cheap, fragrant and readily available. If you cook or bake a lot, you know how common vanilla extract is in sweet foods (it's in everything from French toast to ice cream). Perfumes often contain pure vanilla extract or oil, while others contain synthetic reproductions of the sweet-smelling fragrance.
Vanilla is one of those iconic scents that people love on its own, undiluted by any other aroma, as well as when it's mixed with other elements and becomes more subdued. Like sandalwood, it's frequently used to make fragrant candles and room fresheners in addition to perfumes.