Have you ever wondered how the internet or Facebook is able to support a billion simultaneous users? This course teaches students the design and implementation of such Internet-scale networks and networked systems. Students learn about the principles and techniques used to construct large-scale networks and systems. Topics in this course include routing protocols, network congestion control, wireless networking, network security, and peer-to-peer systems. Upon completing this course, students are able to initiate and critique research ideas, implement their own working systems, and evaluate such systems. To make the issues more concrete, the class includes several multi-week projects requiring significant design and implementation. The goal is for students to learn not only what computer networks are and how they work today, but also why they are designed the way they are and how they are likely to evolve in the future. Examples are drawn primarily from the internet.