What is Firestore?

Cloud Firestore (commonly called Firestore) is Google's flexible, scalable NoSQL document database built for mobile, web, and server development. It stores data as documents organized into collections. Key features: (1) Real-time sync — clients subscribe to data and receive updates in real time as data changes; (2) Offline support — local data caching allows apps to work offline and sync when reconnected; (3) Scalable — scales automatically from developer projects to planet-scale applications; (4) Flexible queries — supports compound queries, ordering, and filtering; (5) ACID transactions — atomic, consistent, isolated, durable operations; (6) Multi-region availability — global distribution with strong consistency guarantees. Firestore replaced the original Firebase Realtime Database as the recommended database for new projects, offering more powerful querying capabilities and better scalability.