Triglycerides are fats. Saturated fats are solid at room temperature while unsaturated fats are liquid at room temperature. This is because these two kinds of fats differ in their chemical structure.
Saturated fats do not have double bonds between the molecules which means there are no gaps and the fat is saturated with hydrogen molecules. Because there are no gaps, these fats tend to pack more closely together.
Unsaturated fats have double bonds which break up the chain of hydrogen molecules and create gaps allowing them to pack loosely and can thus liquefy at room temperature.
