This chapter delves into what a computer does best: do something over and over again. Unlike some programming languages such as C, JavaScript, or Python where the for and while loops provide a construct for repetition, in Haskell recursion is the primary technique in which we repeat a block of code. Recursion is not an easy concept to wrap your head around once you have a habit of looping with for and/or while. For this reason, the section Some examples provides several examples to help you get started on thinking recursively. In the section No loop for you, we will consider various Haskell functions that allow us to write recursive code. The section Fold under pressure presents an immensely useful technique to transform a (complicated) recursive definition to a simple expression. Finally, in the section Recursion by numbers, you will be shown a number of advice to help you write recursive functions in Haskell.