API Glossary

API

An application programming interface is a contract that lets software systems request data or trigger actions from another system.

Example: A weather app calls an API to get the current forecast instead of storing weather data itself.

REST API

A REST API uses standard HTTP methods and resource URLs to read, create, update, or delete data.

Example: GET /api/v1/current-time requests the current time resource.

Endpoint

An endpoint is a specific URL where an API accepts requests for one operation or resource.

Example: https://datpaq.com/api/v1/user-avatar is an endpoint for generating an avatar.

HTTP Method

An HTTP method tells the API what kind of action the client wants to perform. Common methods include GET, POST, PUT, PATCH, and DELETE.

Request

A request is the message a client sends to an API. It can include a method, URL, headers, query parameters, and a body.

Response

A response is the message an API returns after processing a request. It usually includes a status code, headers, and data.

JSON

JavaScript Object Notation is a lightweight data format commonly used by APIs because it is easy for humans to read and software to parse.

API Key

An API key is a secret credential that identifies the application or user making an API request.

Example: DATPAQ examples pass API keys in the x-api-key request header.

Authentication

Authentication is how an API verifies that the caller is allowed to access protected resources.

Authorization

Authorization determines what an authenticated caller is allowed to do, such as read data, create records, or manage account settings.

Header

A header is request or response metadata sent separately from the body. Headers often carry API keys, content types, and caching instructions.

Query Parameter

A query parameter is a key-value pair appended to a URL after a question mark to filter or configure an API request.

Example: name=Jerod in /api/v1/user-avatar?name=Jerod is a query parameter.

Path Parameter

A path parameter is a dynamic value inside the URL path, often used to identify a specific resource.

Example: The {id} segment in /api/users/{id} is a path parameter.

Request Body

A request body is structured data sent with a request, most often with POST, PUT, or PATCH operations.

Status Code

A status code is a numeric result returned with an HTTP response. It tells the client whether a request succeeded, failed, or needs another action.

Example: 200 means success, 400 means a bad request, 401 means unauthorized, and 429 means rate limited.

Rate Limit

A rate limit controls how many API requests a caller can make during a time window to protect reliability and fair usage.

Pagination

Pagination splits a large result set into smaller pages so clients can load data efficiently.

Idempotency

An idempotent request can be repeated without changing the final result beyond the first successful call.

Example: Retrying the same DELETE request should not delete additional resources.

Webhook

A webhook is an outbound HTTP request sent by one system to notify another system when an event happens.

SDK

A software development kit packages helper code, types, and examples so developers can call an API more easily from a specific language.

OpenAPI

OpenAPI is a standard format for describing REST APIs, including endpoints, parameters, authentication, and response schemas.

CORS

Cross-Origin Resource Sharing is a browser security mechanism that controls whether a webpage can call an API on another origin.

Latency

Latency is the time between sending an API request and receiving a response. Lower latency usually means a faster user experience.

Uptime

Uptime is the percentage of time an API is available and responding successfully.

SLA

A service-level agreement defines measurable service commitments, often covering uptime, support response times, and reliability targets.

Schema

A schema describes the shape, fields, and data types expected in an API request or response.