Recently, one-dimensional nanostructures that include fibers, wires, rods, belts and tubes have attracted rapidly growing interest due to their fascinating properties and unique applications. Among them, electrospinning is a highly versatile technique to prepare continuous fibers with diameters of the order of nanometers. It is the most famous technique for the production of high aspect ratio nanofibers. The remarkable high aspect ratio and high porosity bring electrospun nanofibers highly attractive to various nanotechnological applications such as filteration, sensors, protective textile, catalysis, wound dressing, drug delivery, scaffolds in tissue engineering, and so on. This book, therefore, addresses a collective summary of the recent progress in developments of the electrospun ultrafine polyamide-6 nanofibers preparation, characterization and their applications. Information of those polymers together with their processing conditions for electrospinning of ultrafine nanofibers has been summarized. We are anticipating that this book certainly drive the researchers for developing more intensive investigation for exploring in many technological areas.