frontend
The part of your product that people touch, like screens and buttons, running on their phone or in a browser.
Think of the shop window and counter where customers interact. The frontend is the visible part of your product: screens, buttons, forms, and the logic that runs on the device.
It matters because this is where people decide if your app feels clear and fast. The frontend calls endpoints, specific web addresses for actions, over HTTPS, the locked version of web traffic, and handles JSON responses, simple text data.
In this course the React Native app is your frontend, and the marketing site is another frontend. Both talk to backends, the services that store data and do heavier work.