This course introduces the cryptocurrencies and blockchain technologies and applications. The course discusses issues related to blockchains and cryptocurrencies and explains how to provide different security. Through algorithms, frameworks, approaches, techniques and mechanisms, this course also provides knowledge on the application of Blockchain technology in finance in general and currency in particular, and also introduces Blockchain's application in other economic sectors, in order to help learners understand and grasp the development trend and application of this technology in the future.