An API is an interface that allows software components to communicate through agreed requests and responses. A web API commonly uses HTTP, the same protocol that supports ordinary browser navigation. REST is an architectural style built around constraints such as a uniform interface and stateless interactions; it is more than a preference for JSON.
Think in resources and representations
Begin with resources that your application manages. A tutorial platform might expose an articles collection and individual articles. A request to GET /articles/42 asks for a representation of one article. That representation could be JSON, but the resource and the data format are separate concepts. Consistent naming helps clients understand an interface.
HTTP methods describe the intended operation. GET retrieves a representation. POST asks a resource to process submitted content, often creating an item. PUT creates or replaces state at a known address. PATCH applies a partial modification according to its patch format. DELETE requests removal. Avoid performing destructive actions in GET requests, which clients may repeat or prefetch.
Make the contract understandable
Use meaningful response status codes and consistent error bodies. A successful creation can return 201 with the new resource’s location. Invalid input, missing resources, and temporary service failures should be distinguishable. Validate both the shape and meaning of submitted data. Publish examples, pagination rules, authentication requirements, and compatibility expectations for clients.
Stateless requests carry the information necessary to understand them without relying on a previous conversation stored inside one application instance. Authentication credentials still need careful handling. Use HTTPS, restrict permissions, and avoid placing secrets in URLs. Authorization checks belong on the server and must apply to each resource, even when the interface hides inaccessible controls.
Where microservices fit
Microservices divide an application into independently managed components, usually around business capabilities. They can support separate deployment schedules and different scaling needs. However, a network boundary adds latency, failures, tracing requirements, and coordination costs. Splitting a small project into many services can make development slower without providing a useful operational benefit.
Start by separating responsibilities within your code. When a boundary becomes stable and there is a concrete reason for independent deployment, consider extracting it. Plan how data ownership, authentication, retries, and observability will work across that boundary. Avoid assuming that a single transaction can update several independent databases as easily as one local database.
A sensible first project is a documented articles API with validation, pagination, and automated checks for access control. Keep its deployment simple, observe how it behaves, and grow the architecture when the workload or team structure justifies it. Clear contracts matter more than the number of services you deploy.
Technical reference: IETF HTTP Semantics: methods and request behavior.