could somebody fully explain a swap file

i was told to enable a swap file on my duo as i am having intermittent boot loading problems. I think due to my cross EPG download. could somebody please explain

A. what a swap file is
B. how they work

i currently have a 1TB HDD for recording movies an 8GB USB for EPG, Picons, timeshift. i am running Vix 3.0.350.

I have been in swap manager and set a 96mb swap file up on my USB. is this correct??........ now what do i do with it???

Thanks in advance for any advice and help!

Swapfile is like swapfile for windows and it creates extra "memory" for the box which can be useful for low memory box like the duo on some occasions - in normal use mem is enough but occaional if have lots of processes or plugins installed it may sometimes struggle hence swapfiles.

So what I've done is this correct?

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