CARBOHYDRATES (Carbs) are one of the three (3) macronutrients needed to sustain life. They are also the preferred energy substrate of your skeletal muscles. Except for fibre they provide 4 calories per gram.
Generally, most people consume adequate levels of carbs in their diet. However, athletes, people with a high metabolism (Ectomorph), individuals trying to gain muscle/weight or physically active people may need to supplement with carbs around training or in addition to meals.