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What Is an API?
An API is a contract that lets programs request and exchange data.
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AiTechWorlds
AiTechWorlds
API development is the practice of designing and building interfaces that let applications exchange data. This visual guide covers endpoints, HTTP methods, status codes, authentication, versioning, documentation, and API best practices.
An API is a contract that lets programs request and exchange data.
A client sends a request; the server returns a response.
An endpoint is a URL that performs a specific action.
GET reads, POST creates, PUT/PATCH update, DELETE removes.
2xx success, 4xx client error, 5xx server error.
Headers, body, and parameters carry the data.
JSON is the standard data format for APIs.
Params filter; the body sends data to create or update.
API keys, tokens, and OAuth control access.
JSON Web Tokens carry signed user identity.
Limit requests to protect the API from abuse.
Return data in pages for large result sets.
Version APIs so changes don’t break clients.
Return clear, consistent error messages.
Good docs (OpenAPI/Swagger) make APIs usable.
Use Postman or tests to verify behavior.
Validate input, use HTTPS, and limit data exposure.
Safe retries need idempotent operations.
REST, GraphQL, and gRPC suit different needs.
Be consistent, predictable, and well-documented.
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