The past year has witnessed the fast growth of investigations on monolayer and few-layer black phosphorous, termed as ‘phosphorene.’ The intrinsic mechanical, electronic, thermal, and optical properties of phosphorene, which have mainly been revealed by computations, endow it with significant potential applications to the fields of electronics, optoelectronics, thermoelectrics, catalysis, and energy storage. In this overview, we summarize the computational investigations on phosphorene from aspects of inherent quality, properties, potential applications, and new allotropes, and manage to interpret what we can know about phosphorene from computations. We hope that this overview would help better understand phosphorene and provide guidance for experimental and computational colleagues to further investigate phosphorene and other novel two-dimensional materials.