1. Microservices

What it is: Small, independent services — each one handles one job.

• Example: User Service, Order Service, Payment Service
• They run separately but work together
• Can be built, updated, and scaled individually

2. Service Discovery

What it is: Like a phonebook for your services.

• Helps services find each other by name, not IP
• If a service moves or restarts, it updates the phonebook
• Tools: Eureka, Consul, etc.

Without this, services don’t know where others live.

3. API Gateway

What it is: A front door to your system.

• All client requests go through it
• It routes requests to the right service
• It also handles:
  • Authentication
  • Rate limiting
  • Logging
• Tools: Spring Cloud Gateway, Zuul, NGINX