API (Application Programming Interface)
Also known as: REST API, API Endpoint
In one sentence
A way for different software programs to talk to each other—like a menu of requests you can make to get AI to do something.
Explain like I'm 12
Like a drive-through menu for computers—you send a request for what you want, and the API delivers it back to you. You don't need to know how the kitchen works.
In context
OpenAI's API lets developers send text prompts and receive AI-generated responses without building their own AI model. You make an HTTP request with your prompt and API key, and the API returns the completion. Companies use APIs to embed AI into their own products—a customer support app might call Claude's API to draft replies, or a translation tool might call Google's API to convert text between languages. Most AI tools you use daily are powered by APIs behind the scenes.
See also
Related Guides
Learn more about API (Application Programming Interface) in these guides:
AI API Integration Basics
IntermediateLearn how to integrate AI APIs into your applications. Authentication, requests, error handling, and best practices.
8 min readPrompting 201: Structured Prompts & JSON Output
IntermediateAdvanced prompting: structured formats, JSON output, few-shot learning, chain-of-thought, and prompt templates for production.
11 min readTool Use and Function Calling
AdvancedEnable AI to call APIs, query databases, and use external tools. Build agentic systems that take actions in the world.
8 min read