The frontend is everything you see and click in your browser or app; the backend is the server-side machinery you never see, storing data and running the rules that make it work. A simple way to remember it: frontend is the shop window, backend is the stockroom and till system behind the wall.
The core difference
Frontend is the user-facing part of a system that runs on your device; backend is the server-side part that handles data, accounts and logic.
- frontend — the part of a website or app running in the user's browser or device, producing what they see: we rebuilt the front end so the site works properly on phones.
- backend — the part running on a server, handling stored data, accounts, calculations and business rules: the back end went down, so the site loaded but nothing would save.
How to tell them apart
Think of a restaurant. The frontend is the dining room: the menu, the tables, the waiter taking your order — everything a customer sees and interacts with directly. The backend is the kitchen: unseen, but doing the actual work of producing what gets served. A frontend developer shapes the HTML, CSS and JavaScript that build that dining room; a backend developer builds the kitchen, wiring up databases and the rules for how orders get processed.
The mix-up usually happens when something breaks and it is not obvious which side is at fault. If a page looks wrong or will not respond to a click, that is typically a frontend bug. If the page looks fine but nothing saves, logs in or loads real data, the fault usually sits in the backend.
