Self-Registration is a service-discovery pattern in which each service instance takes responsibility for announcing itself to the service registry when it starts, keeps that registration alive while it is healthy,...
Server-side discovery means the caller does not look up service instances at all.
Client-Side Discovery means the *caller* is responsible for finding a service instance.
A Service Registry is a live "phone book" for your services.
A Backend for Frontend (BFF) is a small server-side application that exists for exactly one kind of client (for example the Angular web app, the iOS/Android app, or a partner portal).
An API Gateway is a single entry point that sits between external clients (browser, mobile app, partner systems) and your internal microservices.
