Metal halide perovskite (MHP) nanocrystals (NCs) have attracted significant attention due to their unique optical and electronic properties. These materials, first discovered in 1893, have seen a resurgence in research, particularly in photovoltaics and optoelectronics. The development of colloidal synthesis methods has enabled precise control over the size, shape, and optical properties of MHP NCs. This review provides an updated overview of the synthesis, post-synthesis modifications, and optical properties of MHP NCs, with a focus on colloidal synthesis techniques. The synthesis of MHP NCs typically involves the hot injection (HI) method, which allows for the controlled growth of nanocrystals by rapidly injecting a precursor into a hot solution. This method enables the production of nanocrystals with narrow size distributions and tunable optical properties. The HI approach has been extended to various MHP NCs, including lead halide perovskites (LHPs) and lead-free alternatives. The ligand-assisted re-precipitation (LARP) method is another widely used technique that offers advantages such as cost-effectiveness and the ability to produce high-quality NCs under ambient conditions. Post-synthesis modifications, such as ligand exchange, phase transformations, and surface passivation, are crucial for enhancing the stability and optical properties of MHP NCs. These modifications can alter the surface chemistry, shape, and phase of the NCs, leading to improved performance in optoelectronic applications. The optical properties of MHP NCs are influenced by factors such as quantum confinement, exciton binding energy, and nonlinear optical effects. These properties are critical for applications in light-emitting diodes (LEDs), solar cells, and photodetectors. Despite significant progress, challenges remain in fully understanding the nucleation and growth mechanisms of MHP NCs, as well as their stability under various environmental conditions. Research continues to explore new synthesis methods and post-synthesis treatments to enhance the performance and stability of MHP NCs. The future of MHP NCs in optoelectronics and photovoltaics depends on overcoming these challenges and further optimizing their properties for practical applications.Metal halide perovskite (MHP) nanocrystals (NCs) have attracted significant attention due to their unique optical and electronic properties. These materials, first discovered in 1893, have seen a resurgence in research, particularly in photovoltaics and optoelectronics. The development of colloidal synthesis methods has enabled precise control over the size, shape, and optical properties of MHP NCs. This review provides an updated overview of the synthesis, post-synthesis modifications, and optical properties of MHP NCs, with a focus on colloidal synthesis techniques. The synthesis of MHP NCs typically involves the hot injection (HI) method, which allows for the controlled growth of nanocrystals by rapidly injecting a precursor into a hot solution. This method enables the production of nanocrystals with narrow size distributions and tunable optical properties. The HI approach has been extended to various MHP NCs, including lead halide perovskites (LHPs) and lead-free alternatives. The ligand-assisted re-precipitation (LARP) method is another widely used technique that offers advantages such as cost-effectiveness and the ability to produce high-quality NCs under ambient conditions. Post-synthesis modifications, such as ligand exchange, phase transformations, and surface passivation, are crucial for enhancing the stability and optical properties of MHP NCs. These modifications can alter the surface chemistry, shape, and phase of the NCs, leading to improved performance in optoelectronic applications. The optical properties of MHP NCs are influenced by factors such as quantum confinement, exciton binding energy, and nonlinear optical effects. These properties are critical for applications in light-emitting diodes (LEDs), solar cells, and photodetectors. Despite significant progress, challenges remain in fully understanding the nucleation and growth mechanisms of MHP NCs, as well as their stability under various environmental conditions. Research continues to explore new synthesis methods and post-synthesis treatments to enhance the performance and stability of MHP NCs. The future of MHP NCs in optoelectronics and photovoltaics depends on overcoming these challenges and further optimizing their properties for practical applications.