The Pentose Phosphate Pathway (PPP) is a metabolic pathway parallel to glycolysis that generates NADPH and ribose-5-phosphate. NADPH is crucial for biosynthetic reactions and antioxidant defense, while ribose-5-phosphate is essential for nucleotide synthesis. This pathway occurs in the cytoplasm of cells and is particularly active in tissues like the liver and adipose tissue. The PPP consists of two main phases: the oxidative phase, which produces NADPH, and the non-oxidative phase, which generates ribose-5-phosphate and other sugars. Enzymes such as glucose-6-phosphate dehydrogenase play a key role in regulating this pathway, linking it to cellular needs for energy and biosynthesis.