> ## Documentation Index
> Fetch the complete documentation index at: https://developers.telnyx.com/llms.txt
> Use this file to discover all available pages before exploring further.

# APIs glossary

> Glossary of API and web service terms including REST, webhooks, authentication, idempotency, rate limiting, and HTTP status codes.

| Term                                    | Definition                                                                                   |
| :-------------------------------------- | :------------------------------------------------------------------------------------------- |
| API (Application Programming Interface) | A set of rules that allows software applications to communicate with each other.             |
| API Documentation                       | Instructions and details on how to use an API.                                               |
| API Key                                 | A token passed in an API call to authenticate the client.                                    |
| Basic Auth                              | Authentication method using a username and password encoded in base64.                       |
| Bearer Token                            | An access token used in the Authorization header.                                            |
| DELETE                                  | HTTP method to delete a resource.                                                            |
| Endpoint                                | A specific URL where an API can access the resources it needs.                               |
| Form Data                               | A way to send key-value pairs, often used with file uploads.                                 |
| GET                                     | HTTP method to retrieve data from a server.                                                  |
| GraphQL                                 | A query language for APIs that enables clients to request specific data.                     |
| gRPC                                    | A high-performance, open-source RPC framework by Google.                                     |
| HTTP                                    | Hypertext Transfer Protocol; the foundation of API communication.                            |
| HTTPS                                   | Secure version of HTTP using encryption.                                                     |
| Header                                  | Key-value pairs in HTTP requests and responses that provide metadata.                        |
| Idempotency                             | The property of an operation to have the same result no matter how many times it is applied. |
| JSON                                    | JavaScript Object Notation; a lightweight data format used in API communication.             |
| JWT (JSON Web Token)                    | A compact and self-contained method for securely transmitting information.                   |
| Multipart                               | A type of form data that allows multiple files or fields to be sent in a single request.     |
| OAuth                                   | An open-standard protocol for authorization.                                                 |
| OpenAPI                                 | A specification for describing RESTful APIs.                                                 |
| PATCH                                   | HTTP method to make partial updates to a resource.                                           |
| POST                                    | HTTP method to send data to a server.                                                        |
| PUT                                     | HTTP method to update an existing resource.                                                  |
| Pagination                              | Splitting API responses into smaller parts or pages.                                         |
| Payload                                 | The actual data sent in a request or returned in a response.                                 |
| REST                                    | Representational State Transfer; an architecture for stateless communication.                |
| RESTful API                             | An API that adheres to the REST architecture.                                                |
| Rate Limiting                           | Restricting the number of API calls a client can make.                                       |
| Request                                 | An action initiated by a client to an API server.                                            |
| Resource                                | An object or representation of something accessible via an API.                              |
| Response                                | The data sent back by the server after processing a request.                                 |
| Route                                   | The path portion of a URL used to access an API resource, excluding the domain and protocol. |
| SDK (Software Development Kit)          | A collection of tools for building applications with an API.                                 |
| Status Code                             | A number indicating the result of an HTTP request (e.g., 200, 404, 500).                     |
| Swagger                                 | A set of tools for developing and documenting OpenAPI specifications.                        |
| Throttling                              | Intentionally slowing down the response rate from the API.                                   |
| Versioning                              | Maintaining multiple iterations of an API (e.g., v1, v2).                                    |
| Webhooks                                | Callbacks sent from the server to the client when an event occurs.                           |
| XML                                     | Extensible Markup Language; another data format used in some APIs.                           |