Back End, Backend, or Back‑End: Which is Correct?

A CMS administration screen has a front end of its own. Editors may call that area "the backend", whilst developers use the same word for the server‑side work behind it.
For a publication‑date field, adding a calendar control lets the editor choose a date. Saving it, checking who may change it, and preventing the public site from showing the article too soon are other parts of the job. Calling it all "backend work" doesn't remove the interface work.
For the spelling, my default is back end as a noun and back‑end before another noun: "the back end" and "back‑end development". Backend is also established technical usage.
An Administration Area or a Server‑Side Responsibility?
Calling the administration area "the backend" distinguishes it from the public site. Editors work there; visitors generally don't. It doesn't tell us where the code runs.
In an architectural discussion, the back end usually means server‑side processing behind an interface: applying business rules, accessing stored data, and coordinating with other systems. Those services might support both the public website and the administration screens.
The back end needn't be one machine or one codebase. An application can use several services, a database, a queue, and a separate identity system. It can also be a single application with a modest database.
Nor is "back end" simply another word for "database". The database stores and retrieves information. Application code may decide who can access it, which operations are allowed, and what should happen next.
The Spelling in a Sentence
The noun and adjective distinction is straightforward in a sentence. "The back end validates the request" names a part of the system. "A back‑end service validates the request" uses the compound to describe the service.
Cambridge's dictionary entry records "back end" as a computing noun and "back‑end" as an adjective. The GCC coding conventions make that spelling distinction explicit for their own documentation.
Django's version 1.8 authentication documentation uses the closed spelling for its replaceable authentication components: "backends". That term appears in the framework's configuration and code as well as its documentation.
I leave those names as Django spells them. Rewriting a setting to suit my punctuation preferences won't help anyone find it in the documentation.
The Publication‑Date Field Still Needs Both
That publication‑date field needs controls the editor can use, somewhere to store the date, permission checks, and a rule for when the public site can show the article. The interface and server code have to agree.
Hiding the article in the public navigation isn't enough if its page remains accessible by entering the address. The publication rule needs to govern access, not just the menu.
My explanation of front‑end development covers the interface responsibilities. They still apply to the CMS editing screen, whatever the team calls it.