5G wireless communications expect to bring both high spectrum efficiency and high energy efficiency. To meet the requirements, various new techniques have been proposed. Among these, the recently emerging index modulation has attracted significant interest. By judiciously activating a subset of certain communication building blocks, such as antenna, subcarrier, and time slot, index modulation is claimed to have the potential to meet the challenging 5G needs. In this article, we discuss index modulation and its general and specific representations, enhancements, and potential applications in various 5G scenarios. The objective is to reveal whether, and how, index modulation may strive for more performance gains with less medium resource occupation.