API & Backend
What Is a REST API and How Does a Backend Use It?
A practical introduction to REST APIs, client-backend communication, and the contracts that make an API reliable.
What does an API do?
An API defines how two software components exchange requests and responses. A web interface, mobile application, payment provider, or data service can communicate through this contract.
The REST approach
REST APIs model data as resources and use HTTP methods to read or modify them. Consistent URLs, status codes, and response formats make integrations easier to maintain.
- GET: read a resource
- POST: create a resource or operation
- PUT/PATCH: update
- DELETE: remove a resource
- HTTP status codes: communicate the result
What happens in the backend?
When a request arrives, input is validated, access permissions are checked, business rules run, and the service communicates with databases or external systems. The result is returned in a stable format the client understands.
Qualities of a good API
Security, performance, and documentation are not finishing touches. Error handling, authorization, rate limits, caching, and observability should be evaluated according to the way the system will be used.
Related Technical Guides
Deepen your understanding with these closely related production architectures and tutorials:
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