Metal halide perovskite semiconductors fabricated with simple low-temperature solution processes are a unique class of materials anticipated for use in photonic devices such as solar cells, light-emitting diodes, and light modulators. The metal halide perovskites in the form of nanocrystals are particularly attracting attention as novel functional materials because of their exceptionally high luminescence efficiencies and wide range of possible luminescence wavelengths. By combining different optical characterization techniques, that is, single-dot spectroscopy, photon correlation spectroscopy, femtosecond transient absorption spectroscopy, and time-resolved photoluminescence spectroscopy, we study the dynamics of excitons, trions, and biexcitons in perovskite nanocrystals. Here, we provide a concise review of recent developments in this research field with a focus on trions in lead halide perovskite nanocrystals. A deep understanding of trion dynamics is especially important because they determine the luminescence properties of nanocrystals and are related to the ionization processes of nanocrystals.