Is online electronic vote (e?Voting), using Internet, secure enough? Could someone view or change my vote? If I pay my taxes online, could my financial information be compromised? How can I ensure that a hostile government does not commit fraud? Is it possible to design a generic, extensible, scalable, reusable and highly secure software architecture to develop an e?Government system? Is the direct democracy through Internet (e?Democracy) realistic? This book, the author’s PhD thesis, tries to solve all these questions. Using UML, it proposes an architecture to implement any e?Government, for any country at any level (local, national, supranational...), and with any political and administrative layout. It includes both administrative (eg: paying taxes) and decision-making procedures (eg: voting), and there are no paper-based traditional processes. This book also finds and catalogues all typical security problems in e?Government and e?Democracy, researching solutions for all of them. Finally, the author proposes a qualitative and quantitative analysis framework, in order to measure the probability and cost of solving a given problem, its probability of occurrence, and its impact.