Chapter Five
Databases
Almost every application stores data somewhere that isn't just a pile of files — it uses a database. This chapter explains what databases are, why two major families exist, why most teams let the cloud run one for them, and where the specialist stores fit in.
Store a short list in a file and it works fine. Store a company's entire customer history — with thousands of people reading and updating it at the same moment — and the file approach falls apart. A database is the tool built for exactly that: organized, searchable, trustworthy storage that handles many users at once.
Five topics map the territory. You will see why databases exist at all, how the two main families (relational and NoSQL) differ, why managed databases are the cloud default, what warehouses and caches add to the picture, and how all the database services line up across AWS, Google Cloud, and Azure.