Answer: Long term storage of energy
Explanation: Triglycerides are the fats or basically lipids which are found in the blood.
They are the source of the long term storage of energy.
They are primarily used as storage of the energy because the its oxidation will produce twice as much energy than the oxidation of the carbohydrates.
Thus it is better to store the energy which we take from the food to store as triglyceride.