Inorganic−organic hybrid halide perovskite crystals have been attracting considerable attention due to their excellent light harvesting properties to convert solar energy into electricity. These systems have excellent optical and electronic properties, including wide absorption spectrum, direct and tunable band gap, low charge recombination rates and high charge carrier mobility. The power conversion efficiency in perovskite-based photovoltaic devices already exceeds 20%. On the other hand, the charge carrier transport mechanism along with optical properties and material stability are still under debate, hampering improvements in the efficiency and durability of photovoltaic devices. In this colloquium, we will present some contributions that our research group has been done on the synthesis, structural, transport, optical, and electronic properties on these hybrid organic-inorganic perovskite crystals.