Having established a foundation with Julia's basic data types and control flow, we now turn to organizing and managing groups of data. Storing individual pieces of information is useful, but many programming tasks require handling multiple values together in a structured way.

This chapter introduces Julia's primary collection types. You will learn about:

• Arrays: Ordered, mutable sequences suitable for lists of items that might change. We'll look at how to create them, access elements by index, and perform common modifications.
• Tuples: Ordered, immutable sequences, ideal for fixed groups of related data where the structure and content are not intended to change after creation.
• Dictionaries: Unordered collections that store data as key-value pairs. This structure allows for efficient data retrieval when you know the key.
• Sets: Unordered collections of unique elements, useful for tasks like checking for membership or performing set-theoretic operations such as unions and intersections.

We will cover how to create, access, and manipulate these collections. You'll gain an understanding of their distinct characteristics, common methods, and typical use cases, enabling you to select the appropriate collection for different data management scenarios. Additionally, we will introduce comprehensions, a concise and expressive syntax for constructing collections.