Recent development of nanoplasmonics has stimulated chemists to utilize plasmonic nanomaterials for efficient and distinctive photochemical applications, and physicists to boldly go inside the "wet" chemistry world. The discovery of plasmon-induced charge separation (PICS) has even accelerated these trends. On the other hand, some confusion is found in discussions about PICS. In this perspective, we focus on differences between PICS and some other phenomena such as co-catalysis effect and plasmonic nanoantenna effect. In addition, materials and nanostructures suitable for PICS are shown, and characteristics and features unique to PICS are documented. Although it is well known that PICS has been applied to photovoltaics and photocatalysis, here light is shed on other applications that take better advantage of PICS, such as chemical sensing and biosensing, various photochromisms, photoswitchable functionalities and nanoscale photofabrication.