Photon blockade is a fundamental nonlinear phenomenon in cavity quantum electrodynamics, enabling deterministic control over single photon or photon streams by suppressing multiphoton excitations. This effect provides a crucial physical mechanism for advancing quantum information science. Current research primarily focuses on two major mechanisms: conventional photon blockade and unconventional photon blockade. The former relies on strong atom-cavity coupling, which induces anharmonic energy level splitting and inhibits multiphoton transitions via spectral nonuniformity. In contrast, the latter exploits destructive quantum interference between multiple excitation pathways, achieving two-photon excitation suppression even under weak coupling conditions, thereby significantly reducing the requirement for strong nonlinearity. The interplay between these mechanisms can further optimize photon blockade performance and greatly enhance its efficiency. In recent years, research has extended into new directions such as nonreciprocal photon blockade and nonlinear dissipation control. These developments not only provide a richer theoretical framework for understanding nonlinear behaviors in quantum optics but also establish technical foundations for quantum information processing, quantum computing, and quantum precision measurements. Additionally, research on multi-photon blockade and its extended mechanisms offers crucial support for developing multi-photon quantum technologies. This review systematically summarizes the implementation schemes and recent progress of single-photon and multiphoton blockade, as well as their extensions. It also highlights their potential applications in single-photon sources, quantum information processing, and quantum networks. Finally, we discuss prospective research directions in the field of photon blockade, including the exploration of novel unconventional blockade mechanisms and their integration into large-scale quantum information systems.