Databases
Database
A database is persistent storage software that saves, organizes, and retrieves structured data reliably across server restarts.
Diagram
App Server ──▶ [Database Engine]
│
┌────┴────┐
│ Tables │ users, orders, posts
│ Indexes │ fast lookups
│ Logs │ crash recovery
└─────────┘In Depth
A database is software that stores data on disk (or memory) and provides structured mechanisms to create, read, update, and delete records — known as CRUD operations.