backend
/ BACK-end /
The backend is the part of an app that runs on the server, out of sight. It holds the data, enforces the rules, and does the real work — checking your password, saving your order, totting up your bill. You never look at it directly; you only ever see the answers it sends back.
Think of a restaurant. The dining room you sit in is the frontend — menus, tables, the friendly waiter. The backend is the kitchen and the back office: where the food is actually cooked, the stock is counted, and the till keeps the money straight. Customers never wander back there, and they don't need to — they just enjoy the meal that comes out.
The two halves talk through an API: the frontend asks ('log this person in', 'give me their orders'), and the backend does the heavy lifting and replies. It's also where the sensitive stuff lives — the database, the passwords, the business logic — kept on the server precisely so it stays out of the user's hands.
Browser ──asks──▶ Backend (server)
├─ check password
├─ read the database
└─ send back: { "orders": 3 }The frontend asks; the backend does the real work on the server and replies.
Frontend = what the user sees and touches; backend = what runs on the server and they never see.