Today we all live and work in a participatory cyberspace. Computers, the data networks that interconnect them, and the services available over the networks make up this cyberspace. As cyberspace invades almost all areas of modern day living, playing, and working, it is becoming more important that people understand its technical and political underpinnings and operations, as well as its capabilities, threats, and weaknesses. This is a companion course to CSCI E-45b. The goal of this pair of courses is to give students the tools they need to understand, use, and manage the technologies involved, as well as the ability to appreciate the legal, social, and political dynamics of this ever expanding universe and the interplay between the cyber and physical worlds. The pair of courses covers the essential elements of computing and the history, structure, operation, and governance of the Internet. This course focuses on the fundamental workings of the digital world. From individual computing devices to the broader Internet, students learn how each piece in this gigantic puzzle comes together to create the digital infrastructure that is the cyberspace of today and tomorrow. In addition, we explore the fundamental concepts, technologies, and issues associated with managing and securing cyberspace.