The most significant way to tackle the energy issue is to convert energy from daily activities into usable electrical energy. The use of batteries, which have a difficult time being recycled and disposed of, does not endorse this idea. There aren’t many energy harvesters for electrical vibration energy harvesting; their manufacture, installation, and maintenance are challenging. Triboelectric nanogenerators (TENG) can act as an alternate energy source in place of batteries for low-power portable electronic devices. TENGs have advantages such as accessible design, low cost of production, and excellent energy efficiency. TENGs can function in various modes, including contact separation, sliding, single electrode, and free-standing modes. The structure of TENGs and their corresponding operating modes can be used for generating electricity, wearable power sources, and sensors. This chapter is focused on an overview of the literature, the basic principles of TENG, manufacturing of TENGs through various working modes, and finally, applications of TENG in self-powered portable and wearable devices and wireless power transmission.