## TL;DR

IndexedDB is a low-level, asynchronous transactional database API for browsers, supporting structured data storage including objects and binary data. Unlike localStorage's synchronous key-value model, IndexedDB handles large datasets (hundreds of MB) with indexed queries and transactions.

## Core Explanation

IndexedDB uses object stores (not tables) and indexes for efficient queries. Transactions auto-commit, and the API is event-driven (though modern ORMs like Dexie.js provide Promise wrappers). Key features: cursor-based iteration, compound indexes, version-based schema migrations. It operates within the same-origin sandbox and respects the browser's storage quota.

## Further Reading

- [IndexedDB API (W3C Recommendation)](https://www.w3.org/TR/IndexedDB/)