Unsaturated fat is a kind of fat. It is different from saturated fat in that it is liquid at room temperature while saturated fat is more solid. Its molecules contains double bonds whose carbon atoms that are not fully saturated with hydrogen. There are two types:
Examples of unsaturated fats are palmitoleic acid, oleic acid, myristoleic acid, linoleic acid, and arachidonic acid. Foods containing unsaturated fats include avocado, nuts, and vegetable oils such as canola and olive oils. Meat products contain both saturated and unsaturated fats.
Unsaturated fat is better for people than saturated fat. Some testing has shown that it can raise a person's HDL ("good" cholesterol) levels.  Unsaturated fat is also very important for a healthy brain.
People think that unsaturated fats are 'healthier' than saturated fats. The United States Food and Drug Administration (FDA) recommended that the amount of unsaturated fat consumed should not exceed 30% of one's daily caloric intake (or 67 grams given a 2000 Calorie diet). The new dietary guidelines have eliminated this recommendation at the request of the meat and dairy industries.
Most foods contain both unsaturated and saturated fats. Food packages promote only one or the other, depending on which is the largest share in the product. So, various unsaturated fat vegetable oils, such as olive oils, also contain saturated fat.