Grothendieck duality made simple

It has long been accepted that the foundations of Grothendieck duality are complicated. This has changed recently. By “Grothendieck duality” we mean what, in the old literature, used to go by the name “coherent duality”. This isn’t to be confused with what is nowadays called “Verdier duality”, and used to pass as “$\mathrm{\ell }$-adic duality”.