In this chapter, different concepts from production to the characterization of carbon nanotubes (CNTs) are described. The construction of the actual chapter mainly starts with the description and comparison of the common synthesis techniques i.e. arc discharge, laser ablation, chemical vapour deposition (CVD), flame synthesis, and silane solution methods for the production of the CNTs, followed by the purification process and application potentials of these nanomaterials. Then, a fundamental demonstration and insight in the atomic structure of main CNT configurations (armchair, zigzag and chiral) is provided. In the subsequent subsection, various defect types, classified into two general groups of macroscopic disorders (curvature, twist and hetero-junction kink) and atomic scale defects (vacancies, impurities, perturbation and Stone-Wales defect), and their influence on the properties of CNTs as well as functionalization of CNTs and harvesting these defects for various applications are elucidated. Finally, the experimental and theoretical CNT characterization approaches are discussed and the pertaining results in the literature are presented. The results from literature reveals the fact that these nanostructures, not only involve different defect and disorder types from their synthesis process which reduce their individual mechanical stabilities and often necessitate purification process for their redundant impurities and by-products removal, but also from their functionalization process in which particular defects i.e. adatom doping and multi-CNT welding through hetero-junctions are intentionally employed for enhancing the properties and functionality of the CNTs for various applications from energy storing, gas detection and materials reinforcement to drug delivery and molecules transportation.