Backend

The backend (also called the server side) is the part of a web application that runs on a server rather than in the browser. It handles data storage, business logic, authentication, payments, email, and every other operation that should not run on the user's device.

Backends expose their functionality to the frontend through APIs. When you click a button and data changes — a new record is saved, a payment is processed, an email is sent — the backend is doing that work.

For vibe coders, AI excels at generating backend code once the data model is clear. Describing your database schema and business rules in plain language produces functional server code quickly. Frameworks like Next.js (with API Routes and Server Actions), Express, FastAPI, and Rails are all well-represented in LLM training data.