The primary objective of this research is to present a comprehensive discussion on the fundamental concepts, innovations, and applications of triboelectric nanogenerators. It describes the various triboelectric nanogenerators' modes and mechanisms. Here, materials and associated development that exhibit triboelectric properties are also examined. Additionally, various triboelectric nanogenerator applications have been discussed. Triboelectric nanogenerators, a revolutionary power generation technology, were introduced in 2012 and are characterized as devices that efficiently generate electrical energy from kinetic energy in the environment. The development of triboelectric nanogenerators has advanced significantly since the invention of this innovative power-generation technology. Moreover, in order to provide a deeper understanding of the technology, the modes include Freestanding Triboelectric-Layer, Single-Electrode, Lateral Sliding, and Vertical Contact-Separation Modes as well as their operating mechanism have been thoroughly examined. Likewise, this study describes and offers concepts for future research on the important applications of TENGs, including high voltage power supply, blue energy, self-power sensors, and micro/nano energy. In conclusion, triboelectric nanogenerator is a crucial and alluring technology with the benefits of low cost, simple structure, easy fabrication, high efficiency, and relatively high output energy. Since a broad range of materials can be adopted, scientists can apply this cutting-edge technology in novel ways. For a more comprehensive understanding of this innovative and ground-breaking technology, numerous fundamental scientific considerations and limitations are also addressed.