1. Aerobic respiration: This is the most common type of respiration, and it requires oxygen. It occurs in the mitochondria of cells and produces a large amount of ATP (adenosine triphosphate), the energy currency of cells. It involves four main steps: glycolysis, the Krebs cycle, the electron transport chain, and oxidative phosphorylation.

2. Anaerobic respiration: This type of respiration does not require oxygen and produces much less ATP than aerobic respiration. It is common in bacteria and other organisms that live in environments with low oxygen levels. The most common type of anaerobic respiration is fermentation, which uses pyruvate (a product of glycolysis) as the final electron acceptor.

Therefore, while there are many pathways within each type of respiration, the two main pathways are aerobic and anaerobic respiration.