This chapter explains the concept of “meta,” one of the essential concept in mastering computational thinking. As a reminder, computational thinking is defined as “thinking like a computer scientist.” Computer scientists use computers as tools to generate new information, and they are constantly considering how to recreate the world’s objects and events within a computer. To do this, they must reflect and observe everything from a higher perspective to represent the world’s objects and events as a program. This act and concept are called meta. Since meta can be a difficult concept, this chapter will explain it using examples from everyday life. Humans use meta-thinking effortlessly and unconsciously but achieving it with a computer is extremely challenging. This is because computers must also handle self-reference—the act of referencing themselves—since all things and events include data about data, knowledge about knowledge, learning about learning, and thinking about thinking. This chapter will carefully explain both meta and self-reference using examples from language, mathematics, and computation.