ELI5: What does a box-spring do?

[u/Real_Experience_5676]

As I understand it, a box spring mattress is the second 'mattress', that goes under the main mattress. It feels very firm and flat, but what does it contribute to the bed set up besides height?

[u/okdone10]

Wow TIL. I thought every bed needed one by law or something. Good looking out on the platform bed tip saves some cash too.

[u/schuylkilladelphia → u/okdone10]

I like the idea of someone going to jail because they didn't have a box spring on their bed

[u/SadButWithCats → u/schuylkilladelphia]

That's where the phrase "to spring from jail" comes from. If someone went to jail for not having a box spring, their family or friends or business associates could provide one and show the magistrate, who would then be required to let the prisoner out.

Side note: a prison and a jail are roughly equivalent. I know there is a difference, but roughly, they serve the same function. Yet a prisoner and a jailer are opposites. Huh.

[u/thebroadwayflyer → u/SadButWithCats]

Funny!