Backend
Also called back end, server side.
The backend is the part of an application that handles work such as data, account checks, and storage behind the interface.
Example
A sign-in form is frontendThe frontend is the part of an application that people see and use, usually in a browser or on a device.. The check that the password matches, and the decision about what the account may edit, are backend.
Why it matters
People do not click the backend directly. The frontendThe frontend is the part of an application that people see and use, usually in a browser or on a device., or another service, sends it requests. Secrets and permission checks belong here when they must stay off the visitor's device.
Common confusion
Backend is not the databaseA database is an organized collection of data that software can store, search, and update. by itself. The database stores data. The backend is the application work that uses it.
Sources
Updated September 30, 2026.