As your programs grow, managing repeated sections of code can become a challenge, leading to inefficiencies and a higher likelihood of errors. Functions address this by allowing you to group code into named, reusable blocks. You can then execute these blocks whenever needed, potentially with different inputs, without duplicating the code. This practice enhances program organization, readability, and maintainability.

This chapter guides you through creating and using functions in Julia. We will cover how to define functions and call them. You'll learn to handle function arguments, including positional and keyword types, and how to assign default values. The chapter also explains how functions return values and how variable scope influences data access. Additionally, you will be introduced to writing concise anonymous functions, the idea of multiple dispatch which is a distinctive feature of Julia, and the importance of documenting functions with docstrings.