This comprehensive volume delves into the transformative world of carbon nanotubes (CNTs), showcasing their unparalleled potential across diverse scientific and engineering disciplines. Leveraging their unique electrical, mechanical, and surface properties, CNTs are revolutionizing areas from advanced sensing to sustainable energy. The book explores the integration of single-walled CNTs into microstructured optical fibers for highly sensitive opto-chemical sensing of volatile organic compounds, and their superior efficacy as adsorbents in environmental remediation and analytical extraction, outperforming conventional materials for pollutants and heavy metals. Furthermore, it details cutting-edge research in energy storage, including the complex mechanisms of hydrogen storage and the development of high-performance supercapacitors. CNT-based supercapacitors, with their exceptional mesoporosity and conductivity, significantly surpass activated carbons, particularly when designed as aligned structures or integrated into innovative hybrid composites with metal oxides and electroactive polymers. The text also highlights their role in futuristic applications like ultralight carbon nanotube membrane solar sails for space propulsion, and the creation of multifunctional CNT-nanoparticle hybrid structures for enhanced catalysis, sensing, and electronics via advanced assembly methods. This book offers a deep dive into the synthesis, characterization, and groundbreaking applications of CNTs, cementing their status as a cornerstone of next-generation technologies.