Linux is an operating system kernel and also refers to computer systems built upon the Linux kernel as well as many other tools and applications. Nowadays, Linux-based systems have been widely used in many places, from supercomputers to tiny embedded systems, from software development to scientific research. Understanding and mastering of Linux systems has become one of the mandatory skills for students from IT-related programmes. Although with search engines, people can find Linux-related knowledge and skills scattered across the Internet, this course aims to give a more systematic introduction to Linux and help students quickly build the thinking models to understand Linux system organization, design philosophy, working model, and useful tools that can boost daily working efficiency.