Firestore integration with Angular or React involves several steps. First, install Firebase and Firestore libraries in your project using npm. For Angular, use AngularFire library for seamless integration. In React, directly import Firestore from Firebase.
Next, initialize Firebase in your application. This requires a configuration object provided by Firebase console. It includes unique keys to connect your app to the Firestore database.
In Angular, inject AngularFirestore module into the constructor of the component where you want to use Firestore. In React, create an instance of Firestore after initializing Firebase.
To read data, use collection() and doc() methods followed by valueChanges() (Angular) or get() (React). These return Observables/Promises respectively which can be subscribed to or awaited to retrieve data.
Writing data involves calling add() or set() on a CollectionReference or DocumentReference respectively.
Remember to handle errors appropriately and close connections when done.