Back-end and front-end are common technical terms nowadays. Traditionally, they are written with a hyphen "back-end". Is there a rule in the English language that dictates this to be a correct way to write term, that signifies general single something? Or did it just "stick" that way?
Clarification 1: The proposed answer that discusses when to hyphenate assumes back-end as a compound word. I don't think it is and this am asking this question. Compound words like on-the-fly are comprised of possible standalone words that are all required to describe the phenomenon or thing in question.
Backend is a synonym to server-side, which really is a compound word. Backend is a singularization of server-side, not a compound itself.
I understand that I may have a logical "gap" somewhere in this line, the reason why I asked is to help me clarify this.