SQLite is a serverless, embedded SQL database stored in a single file. It is ACID compliant and requires zero configuration. Databases use files like .db or .sqlite. Use the sqlite3 CLI to run commands. Core commands include CREATE TABLE, INSERT, SELECT, UPDATE, and DELETE. Types use manifest typing with flexible affinity. Transactions with BEGIN, COMMIT, ROLLBACK ensure durability. Common uses include mobile apps and local storage. Write concurrency is limited by file locking.