Anthropic is the AI company that makes Claude. Founded by former OpenAI researchers, they focus heavily on safe, honest, and controllable models. Their flagship models are the Claude family (Opus, Sonnet, Haiku).
An API (Application Programming Interface) is the door that lets software A send a request to software B and get a structured answer back. "Using the OpenAI API" means: your tool talks to ChatGPT's brain programmatically, without the chat window.
EXAMPLEYour CRM pulling weather data to personalize an email is one app calling another app's API.
An API key is a long string that identifies your account when one program calls another's API. Treat it like a credit card: don't share it, don't commit it to GitHub, rotate it if it leaks.
A chatbot is the interface most people use to talk to an AI — a chat window with a message box. ChatGPT, Claude, and Gemini are chatbots. You type, it replies, you refine, repeat.
ChatGPT is OpenAI's consumer-facing chatbot, launched November 2022. It was the product that pushed modern AI into the mainstream. Runs on the GPT family of models underneath.
Claude is a family of AI models made by Anthropic, available via Claude.ai and an API. Popular with technical and commercial teams for long-document work, writing, and coding.
Copilot is the brand Microsoft uses for AI assistants inside its products. You'll meet it as the sidebar in Word, the "/copilot" button in Teams, and a standalone app on Windows. Runs primarily on OpenAI models under the hood.
An endpoint is a URL an API exposes for a particular purpose. One endpoint generates text, another creates an image, another fetches billing. The URL path (/v1/messages) tells the server what you're trying to do.
Gemini is Google's AI chatbot and underlying model family. Lives at gemini.google.com and is also baked into Workspace (Gmail, Docs, Sheets). Good at web-connected tasks thanks to Google Search integration.
OpenAI is the San Francisco company that makes ChatGPT and the GPT series of models (GPT-4, GPT-5, etc). They sell both the consumer chatbot and an API for developers.
regex
also: regular expression, regular expressionsRegex (regular expressions) is a tiny language for matching patterns inside text. You rarely need to write one — AI is extremely good at it. "Give me a regex that finds US phone numbers" is a good prompt and a big time-saver.
An SDK (Software Development Kit) wraps an API in ready-made functions for a specific language — Python, JavaScript, etc. Instead of hand-crafting HTTP requests, you import a library and call openai.chat.completions.create(...). Less code, fewer bugs.
streaming
also: streamed, streamStreaming is why ChatGPT appears to "type" at you. The answer is generated and sent token by token, which feels faster and lets you interrupt early if you can already see it's going wrong.
A webhook is a "call me when something happens" hook. You give Stripe your URL; when a payment succeeds, Stripe sends a little message to your URL. Webhooks are how automations trigger immediately instead of polling.