This book provides a comprehensive overview of the recent development of flexible electronics. This is a fast evolving research field and tremendous progress has been made in the past decade. In this book, new material development and novel flexible device, circuit design, fabrication and characterizations will be introduced. Particularly, recent progress of nanomaterials, including carbon nanotubes, graphene, semiconductor nanowires, nanofibers, for flexible electronic applications, assembly of nanomaterials for large scale device and circuitry, flexible energy devices, such as solar cells and batteries, etc, will be introduced. And through reviewing these cutting edge research, the readers will be able to see the key advantages and challenges of flexible electronics both from material and device perspectives, as well as identify future directions of the field.