API terms, in plain language.
Use this glossary to build a shared vocabulary for API discovery, request design, authentication, and AI integrations. The related field notes put these concepts into a practical workflow.
API
An application programming interface defines a way for software components to interact. A web API commonly exposes operations or resources through a network request.
Endpoint
A documented address or route through which an API exposes a resource or operation. The method and request data are part of its usage contract.
Authentication
The process that establishes the identity or credential associated with a request. Authentication is distinct from permission to perform a particular action.
Authorization
The rules that determine which actions and data an authenticated identity may access. An accepted credential does not necessarily permit every request.
Bearer token
A credential presented by a client to obtain access. Anyone who possesses a valid bearer token may be able to use the access associated with it.
Rate limit
A provider-defined restriction on the amount or frequency of activity. The relevant limits and the response to exceeding them depend on the service.
Idempotency
A property describing operations whose intended effect remains the same when repeated. Retry decisions must follow the documented behavior of the specific operation.
LLM token
A unit in the representation used by a language model. Token counts depend on the model and tokenizer, and are not generally interchangeable with word counts.
Context window
The amount of context a model can process within the applicable request. The provider’s contract determines what content and output allowances count toward its limits.
Prompt
Instructions and supplied context that describe the work a model is asked to perform. A useful prompt connects a clear task with an output that can be evaluated.
Embedding
A numeric representation of content used for tasks such as similarity or retrieval. Its quality is assessed in relation to the downstream task.
Webhook
A mechanism through which a service sends an event notification to an endpoint configured by another application. Receipt, verification, and processing are separate steps.
SDK
A software development kit provides tools or libraries for working with a service or platform. Its support for retries, authentication, and error handling should be checked.
Pagination
A way to retrieve a collection in smaller portions. The next portion may be identified by a cursor, page number, link, or another provider-defined mechanism.
Connect the terms with practice
Use the authentication field note, LLM token guide, and first-request workflow to explore these concepts in context. Each guide includes an official supporting reference.