What is "projection formula"

In algebraic geometry, the projection formula states that, for a quasi-compact separated morphism of schemes f : X → Y, a quasi-coherent sheaf F on X, a locally free sheaf E on Y, the natural maps of sheaves

RfF ⊗ E → Rf(F ⊗ fE)
are isomorphisms.

There is yet another projection formula in the setting of étale cohomology.