Back end? Front end?

Question

What is the difference between backend and front end?

Answer 1

The frontend comprises of the user interface, controls and every part of the application presented to the user.

The backend is the part of the application that is only accessible by the admin.

Answer 2

The front end are called “client-side” programming, is what happens in the browser. It's everything the user sees and interacts with.
The back end are called “server-side” programming, happens on the server and the database.