This is THE only comprehensive book on the nature, history, and impact of signatures, written by a pioneer in the signature space. This expert resource explains the development of signatures, the implementation of digital signatures, the goals of signatures--authenticity, non-repudiation, and data integrity--and gives insight into signature frauds. It discusses the role of notaries in the process, including the well recognized systemic issues with pen-and-ink notarization in the 2010 robosigning frauds, and discusses practical ways to bring signatures into the future.