Yes, Yes, I know that the title is poorly written.
It should be "15 Things of which you don't know the purpose."
But that is how it was written on the youtube link where it is found.
Apparently English is not being taught in schools anymore.
Sigh.
But the 15 things ARE interesting and you will likely learn something new
so
HERE'S THE LINK to (gasp) 15 things you don't know the purpose of