Before building systems to manage data, it's necessary to understand the raw materials. This chapter introduces the basic building blocks data engineers handle.

You will learn to distinguish between structured, semi-structured, and unstructured data. We will look at common origins of data and methods for gathering it. Key storage structures like relational databases, NoSQL databases, data warehouses, and data lakes will be defined. We will also briefly touch upon using APIs to retrieve data. The chapter includes a practical exercise for identifying different data forms. Grasping these fundamentals provides a solid base for understanding data pipelines and storage solutions covered later.