What is an API? How applications request functions and data
Use model text processing to explain API inputs and responses, distinguish SDKs and UIs and check real results.
Understand the concept
An API defines how programs call functions or exchange data through agreed inputs, results and errors. It need not be a web interface or AI-specific. An address does not grant access and a successful status does not validate business content; check the requested result.
An interface connects callers to implementations
A model service defines text, model identifiers and parameters and returns content and usage. Callers need not control internals but must follow fields and authentication. OpenAI references define requests while SDKs wrap them in language functions. Similar fields across providers do not establish equivalent capabilities or migration compatibility.
A classification request needs its complete response checked
Submit a public sentence for a fixed label, check request and response structure and verify the label against known examples. Separate rejected requests, malformed outputs and classification errors. Documentation examples are not current application runs. No external call occurred here. For writes, verify target records rather than trusting a textual completion message.
Versions affect parameters and downstream handling
Version changes can alter fields, model support and responses. Preserve versions and replayable examples and check SDK and service upgrades separately. Costs include calls, integration, timeouts and duplicate handling. Define inputs, errors and acceptance, not just URLs. SDK and HTTP approaches both require understanding the service contract.
Checked sources
These sources support the concepts and methods described here. Examples and test scope are labeled separately; check the version of the tools you use.