As the world is marching into the era of the internet of things (IoTs) and artificial intelligence, the most vital development for hardware is a multifunctional array of sensing systems, which forms the foundation of the fourth industrial revolution toward an intelligent world. Given the need for mobility of these multitudes of sensors, the success of the IoTs calls for distributed energy sources, which can be provided by solar, thermal, wind, and mechanical triggering/vibrations. The triboelectric nanogenerator (TENG) for mechanical energy harvesting developed by Z.L. Wang's group is one of the best choices for this energy for the new era, since triboelectrification is a universal and ubiquitous effect with an abundant choice of materials. The development of self‐powered active sensors enabled by TENGs is revolutionary compared to externally powered passive sensors, similar to the advance from wired to wireless communication. In this paper, the fundamental theory, experiments, and applications of TENGs are reviewed as a foundation of the energy for the new era with four major application fields: micro/nano power sources, self‐powered sensors, large‐scale blue energy, and direct high‐voltage power sources. A roadmap is proposed for the research and commercialization of TENG in the next 10 years. Triboelectric nanogenerators (TENG), which utilize the universal triboelectrification for harvesting ambient and biological mechanical energy, has attracted worldwide interest and undergone exponential growth since its invention in 2012. This article reviews the fundamentals and applications of TENG as a foundation of the energy for the new era, and proposes a road map for its research and commercialization in the next decade.