Anabolism is that aspect of metabolism which involves the building up, inside cells, of complex molecules from simpler substances, with the absorption and storage of energy. An example is photosynthesis, in which solar energy is incorporated into complex compounds such as glucose and its derivatives. Non-photosynthetic anabolism is primarily driven by the energy stored in ATP (adenosine triphosphate) molecules. The converse of anabolism is catabolism.
Catabolism is that part of metabolism concerned with the breakdown of complex substances into simple ones and the consequent release of energy.