What is the purpose of anaerobic and aerobic respiration?

Both aerobic and anaerobic respiration involve chemical reactions which take place in the cell to produce energy, which is needed for active processes ... Anaerobic respiration also produces energy and uses glucose, but it produces less energy and does not require oxygen.

The purpose of respiration in general is to turn food into energy that a living biological cell can use. Anaerobic respiration is respiration that uses any molecule besides oxygen to do this. Many bacteria use anaerobic respiration.