Frontend

The part of an application that runs in the visitor's browser and handles everything they see and click, such as buttons, forms, layouts, and on-screen feedback.

The frontend is the part of an application that runs in the visitor's browser and handles everything they see and click. It is the screens, buttons, forms, and layouts a person interacts with directly, plus the code that responds when they type or tap. Picture a password reset page: the form fields, the show-password toggle, the message that says the email does not match, and the spinner while it waits are all frontend. The browser runs that code on the visitor's own device, so two people on the same page can each see their own typing and validation without anything going back to a server yet.

Builder example

When you ask an AI assistant to build a to-do app, the part it writes for the browser is the frontend: the input box, the list, the checkboxes, and what happens when you click one. Confusing this with server work leads to mistakes like keeping a secret key in browser code, where anyone can read it. Tell the assistant which behavior belongs in the browser and which needs a server, so sensitive logic stays out of the frontend.

Common confusion: The frontend is what runs in the browser, and the backend is what runs on a server. A page can look finished while its frontend still depends on backend code for live data or sign-in, so a frontend that loads is not proof the whole feature works.