Book excerpt: This is the very first book on the highly promising topic of MXenes; focusing on their fundamental characteristics and properties, fabrication techniques and applications. MXenes are two-dimensional materials consisting of few atoms thick layers of transition metal carbides or nitrides. These are characterized by high electrical conductivity, good hydrophilicity, chemical stability, and ultrathin 2D sheet-like morphology. Applications in the energy, environmental, biomedical and electronic industries include catalysis, membrane separation, supercapacitors, hybrid-ion capacitors, batteries, flexible electronics, hydrogen storage, nanoelectronics, and sensors.