Truffles are a fungus and belong to the mushroom family. They grow underground near trees in very wooded areas. The truffles get their flavor from the trees they grow beneath and they have a much earthier flavor than your typical mushroom. They are harvested by pigs who sniff them out from deep in the ground. The harvesting process is what makes them so expensive. Truffle oil is olive that has been infused with truffles.
Truffle oil (white or black) should be used sparingly, as the flavor is strong and is not an oil to cook with. Think more of a finishing oil.
Here are some great ways to use truffle oil:
1) In vinaigrette: If you’re making a fancier salad, combine a teaspoon or two of truffle oil with some olive oil, lemon juice, salt and pepper. It tastes great on a salad with fresh or sauteed mushrooms. This would not be good on a salad with fruit in it as it is a savory product. 
2) Over vegetables: You can drizzle some oil over already cooked vegetables. It tastes great on starches, like potatoes, and greens. It also goes great over asparagus.
3) On party snacks: If you’re serving home made after dinner snacks like popcorn, french fries, or potato chips, drizzle on a mixture of truffle, olive oil and salt.
Hope this will inspire you to try something new and different. Remember a little truffle oil goes a long way. Happy cooking!