What is SQLite?
SQLite is a complete SQL database contained in a single file — no server to run, no setup, no configuration. Your whole database is one .db file you can copy, email, or commit. It is the most widely deployed database in the world (it is inside your phone, your browser, and countless apps).
When should you use it?
Perfect for learning SQL, for small-to-medium apps, for desktop and mobile apps, and for prototypes. Use it when you do not need multiple servers writing at once. When you outgrow it, the SQL you learned transfers directly to PostgreSQL.
How to set it up
Nothing to install — it is built into Python (import sqlite3) and most languages. The database is created the first time you open a file.
How it connects to your code
In Python: conn = sqlite3.connect("app.db"), then run SQL with conn.execute(...). That is the entire setup.