 Carbon nanofibers, CNF, have become increasingly popular due to their unique physical and chemical properties. They can be used in a variety of applications, such as electrical devices, electrodes for batteries and supercapacitors, and sensors. Their electrical properties depend heavily on the percolation threshold, which is determined by the aspect ratio, fractal characteristics, and percolation backbone structure of the CNFs. Additionally, the thermal and mechanical properties of CNF composites are also discussed. Preparation methods include catalytic chemical vapor deposition growth and electrospinning, while preparation methods include melt mixing and solution processing. Finally, CNF composites are used as sensors and electrodes for batteries and supercapacitors. This article is authored by Li Chaofeng, Ning Xie, and Jing Zhang.