What Are APIs, Frameworks, and Hosting?

When you start building products, you'll encounter these terms constantly.

API — The connection

Allows your application to send requests to a model or external service and receive results.

Example: Your website sends a prompt to a hosted LLM API.

Framework — The development tools

A collection of code and abstractions that makes it easier to build applications or agents.

Examples: LangGraph, LlamaIndex, and model-provider SDKs.

Hosting — Where it runs

The infrastructure that runs your website, backend, database, or model.

Examples: Vercel for many web applications; GPU cloud servers for models that need substantial GPU resources.

Database — Where information is stored

Stores users, preferences, conversations, application data, and other records.

Examples: PostgreSQL and MongoDB. A vector database can help retrieve semantically relevant information.

These components solve different problems. You can use a hosted LLM API without hosting the model yourself, or you can download a suitable open-weight model and run it on your own infrastructure.