Diffraction Phase Microscopy (DPM) is a widely used quantitative phase imaging method, whose common-path nature endows it with low noise and high sensitivity. Current applications of DPM include biological topography as well as biological dynamics for its nondestructive feature. Many different forms of DPM based on the original idea have appeared according to the different demands. In this paper, both the principle and the DPM classification will be given a comprehensive description. Furthermore, the future trend of DPM development is also discussed.