Know the fats by their names. Eat good fats, avoid the harming fats.
For the last forty years fats have been shown to increase heart disease and cancer and have been under relentless attack from nutritional-scientists and food industry. As a result every food has a word fat, saturated fat, cholesterol and now days also trans fats on the Nutrition facts on it.
Saturated fats tend to be solid at room temperature. The major sources of saturated fats are butter, lard, ghee, meats (beef, pork, chicken, lamb), dairy, coconut oil (will talk more about this oil later), and pastry made from butter or chocolate. Margarine also contains significant levels of saturated fats, but is to be condemned for other reasons (see the discussion on trans-fats, below).
Cholesterol frequently is present with these fats, but can also be found separately, such as in egg yolk.
Monounsaturated fats are the healthiest for the heart and cholesterol levels. Monounsaturated fatty acids or MUFA are the main constituent of olive oil. Canola oil and peanut oil and certain nuts, like walnuts and pecans also contain preferentially monounsaturated fats. It is well known that, traditionally, people consuming a Mediterranean diet have lower rates of heart disease. The Mediterranean diet is a high monounsaturated fat diet because everything is cooked or dressed with olive oil. The studies comparing high MUFA diets with the traditional American-Western diet showed dramatic differences, including better patterns of insulin sensitivity, cholesterol profiles, heart disease and weight. High MUFA diets lower bad LDL-cholesterol without harming levels of good HDL-cholesterol. In contrast, very low-fat diets have shown very modest and transient weight reduction, with a decrease in HDL or “good” cholesterol. The moral of the story: Don't try to eliminate fats completely because they are important. Use olive oil as your preferred oil.
Polyunsaturated fats are found in vegetable oils, canola oil, flax oil, peanut butter, almond butter and fish oil. As it turns out, unsaturated fats tend to be associated with lower cholesterol, when compared with saturated fats.

Trans fats are unknown to nature. These are created in the lab under high temperatures, by reintroduction of hydrogen atoms into fatty acid chains, causing double bonds to randomly convert into single bonds. This process is called hydrogenation and many foods on the market contain hydrogenated or partially hydrogenated fats. These fats contain trans fatty acids. Trans-fats are the worst fats health wise. We can't (or at least shouldn't) use them the way we usually use fats (to build cell membranes, nerve coating, hormones). They are one of the major culprits of weight gain. They raise the bad LDL-C and lower the good HDL-C. Vegetable shortening is another name for these fats.
These partially hydrogenated fats give foods the properties of long shelf life. If you buy pastries made with these compounds and accidentally lose them in the back of your cupboard, you will note that they still appear fresh months and years later. Processed foods—margarine, snack foods, French-fries, shortenings and cheap baked goods, are main sources of trans-fats. Previously thought to be harmless (remember when margarine was “better” than butter?) these trans-fats are shown to harden the arteries and express other harmful effects (like suppression of immunity) on the body. The direct correlation has been shown between the eaten hydrogenated fat and body fat. On a scale from -10 to 1, one being good and -10 being bad, trans-fats score -10, saturated fats score -5, polyunsaturated fats score 1 and omega-3 fatty acids are positive 5. In fact those are so good that we will dedicate a week to Omega-3s.