Trans-fats are created using synthetic processing to break down natural oils into semi-solid fat by adding hydrogen atoms to unsaturated fat molecules. Trans-fats are chemically processed and are to be avoided; they are bad for your health. Please read product labels and do not buy or eat foods containing these oils. To simplify this potentially confusing issue: buy and use only extra virgin olive oil, organic and preferably raw butter, virgin raw coconut butter/oil and high lignin flax seed oil.
Understand that heat destroys all fats and oils to a greater or lesser degree. It is best to cook food with little to no oil, ideally adding oils for flavor after the food is cooked. Coconut butter/oil is stable at high heat levels and is best for cooking. Make your own healthy salad dressings using extra virgin olive oil and avoid fried foods. Raw, unheated fats and oils are the healthy fats you want in your diet.