Fat is sexy. That is, when you cook with it. Fats and oils are integral to cooking because they not only transfer heat, they add an abundance of flavor. There are two main types of fats: solid fats, including animal fats and butter, and liquids, like olive oil. Vegetable oil is the most common oil used in households. It has a neutral flavor.
I primarily use the following lubes when cooking: unsalted butter, extra virgin olive oil and canola oil.
I love unsalted butter because it tastes wonderful, especially if it's organic. Unsalted butter is of a higher quality then salted, and gives you better control over seasoning your foods. In terms of health, butter offers sources of Vitamin A and other fat soluble vitamins such as E, K, and even D. It’s made from natural ingredients and not chemically or artificially processed. It's also very versatile; I use butter for everything from frying eggs to sautéing mushrooms. Butter is essential in creamy sauces, marinades, baked dishes, casseroles, wonderful in pasta, baked goods and of course on some fresh hot bread or toast. I love to cook with butter and extra virgin olive oil together, which is a very Italian way of cooking.
Extra virgin olive oil is dead sexy, and has a lovely distinct flavor. These oils can vary depending on where the olives are grown and how the oil is manufactured. The oil is rich in monounsaturated fat, helps to lower cholesterol levels and reduce risk of cancer. It's also rich in antioxidants and has a very long storage life.
If you just want to add flavor to your dish, add the oil at the end of cooking. Extra virgin olive oil can be used in cooking and it's the healthiest choice when uncooked, such as with a salad or dipping sauce. When you use it for cooking, you should use a low to medium flame, making sure to avoid high heat. The flavor breaks down when frying so you may just want to use regular olive oil.
When I need a more neutral flavor (e.g. sautéing), I turn to Canola oil. It is the healthiest of all commonly used cooking oils. Of all the popular oils, it's the lowest in saturated fat, high in cholesterol-lowering, mono-unsaturated fat, and is the best source of omega-3 fats. It has a high smoking point, which means that you can use it at higher temperatures.
An oil’s ‘smoke point’ indicates how high a heat the oil can take before it begins to smoke. When oil smokes, it releases carcinogens into the air and free radicals within the oil. This is not a good thing!
Store oils at room temperature in a dark place. Direct sunlight will kill the oil.
For a more in depth look at oils and their usage, check out the cooking with fats and oils section in the Cooking 101 section.