Blockchain promises to disrupt industries once it will be efficient at large scale. In this course, you will learn how to make blockchain scale. You will learn about the foundational problem of distributed computing, consensus, that is key to create block securely. By illustrating limitations of mainstream blockchains, this course will indicate how to improve the technology in terms of security and efficiency. In particular, this course will help you: * understand security vulnerabilities of mainstream blockchains; * design consensus algorithms that tolerate attacks, and; * design scalable blockchain systems.