What is the equation for the phosphate buffer system?

The equation for the phosphate buffer system is HPO4^2- + H2O ↔ H2PO4^- + OH^-. The system involves the dihydrogen phosphate ion (H2PO4^-) acting as a weak acid and the hydrogen phosphate ion (HPO4^2-) acting as its conjugate base, helping to maintain pH stability in biological systems.