Photoacoustic microscopy (PAM) is a noninvasive imaging technique that has undergone remarkable advancements and applications in the field of life sciences, basic medical research, and medical diagnostics. It operates on the unique principles of detecting photoacoustic signals and reconstructing them to create high-resolution, in-depth structural and functional images. This paper offers a comprehensive overview of the developmental background and unique principles behind photoacoustic microscopy. As we delve deeper, we explored various methods that have been employed to boost imaging performance. These include, but are not limited to, optical enhancement, acoustic enhancement, exploitation of artificial intelligence to augment the entire process. Moreover, there has been a significant focus on the harmonious integration of optics and acoustics in PAM. Ultimately, we discussed the extensive applications of current PAM in modern biomedical research and provided insights into the future developmental trends of this technique.