First and foremost it is client side SDK's (web, mobile) for their database products, their newest being Firestore that provides better query capabilities compared to their original Firebase Realtime database (while still offering real-time capabilities).
Along with that is Firebase Authentication, which manages user accounts and authentication.
The real magic comes in with Cloud Functions (their version of Lambda) which allows for hooks in to all sorts of events occurring from usage of these database and authentication products (and other cloud services).
Hook into database writes, updates, deletes, user creation, Google Cloud's pub-sub events and many more. They also offer static website hosting as well as hooking website serving into cloud functions (for server side code execution).
In the context of a website, all of these work together to allow for usage of the JAMstack[0] architecture which decreases your infrastructure resources you need to manage and cost.
First and foremost it is client side SDK's (web, mobile) for their database products, their newest being Firestore that provides better query capabilities compared to their original Firebase Realtime database (while still offering real-time capabilities).
Along with that is Firebase Authentication, which manages user accounts and authentication.
The real magic comes in with Cloud Functions (their version of Lambda) which allows for hooks in to all sorts of events occurring from usage of these database and authentication products (and other cloud services).
Hook into database writes, updates, deletes, user creation, Google Cloud's pub-sub events and many more. They also offer static website hosting as well as hooking website serving into cloud functions (for server side code execution).
In the context of a website, all of these work together to allow for usage of the JAMstack[0] architecture which decreases your infrastructure resources you need to manage and cost.
[0] https://jamstack.org/