Nutrition supplies three physiological needs:
1) Fuel for cellular energy.
2) Raw materials so the body can make it's own molecules.
3) Essential nutrients which the body can't make so must be supplied by the diet.
Macronutrients are needed in large amounts and are seen to be carbs, proteins (amino acids), and fats (essential fatty acids).
Micronutrients are needed in much smaller amounts and are needed for enzymatic activity. They are divided into 2 groups: vitamins (organic, carbon based componds) and minerals (metal ions from inorganic elements).