Carbon nanotubes (CNTs) were discovered by Iijima  as elongated fullerenes in 1991. Since then, research on growth, characterization, and application development has exploded due to the unique electronic and extraordinary mechanical properties of CNTs. The CNT can be metallic or semiconducting, and thus it offers possibilities to create semiconductor-semiconductor and semiconductor-metal junctions useful in electronic devices. The high-tensile strength, Young’s modulus, and other mechanical properties hold promise for high-strength composites for structural applications. Researchers have been exploring the potential of CNTs and making progress in the past decade in a wide range of applications: nanoelectronics, sensors, field-emission-based displays, batteries, polymer matrix composites, reinforcement material, and electrodes, to name a few. In this chapter, an overview of this rapidly emerging field is provided. First, the structure of the nanotube and properties are explained. Unlike many other fields in science and engineering, the evolution of CNTs to its current level owes significantly to the contributions from modeling and simulation. Computational nanotechnology has played an early and major role in predicting as well as explaining the interesting properties of CNTs. So, a section is devoted to modeling and simulation after the description of the properties. Then, nanotube growth is covered in detail followed by material development functions such as purification, characterization, etc. Finally, a review of the
current status of various applications is provided. For a detailed discussion on all these aspects, the reader is referred to a recent textbook .