  This note is a summary of our work [OO] which provides an explicit and global
moduli-theoretic framework for the collapsing of Ricci-flat Kahler metrics and
we use it to study especially the K3 surfaces case. For instance, it allows us
to discuss their Gromov-Hausdorff limits along any sequences, which are even
not necessarily "maximally degenerating". Our results also give a proof of
Kontsevich-Soibelman [KS04, Conjecture 1] (cf., [GW00, Conjecture 6.2]) in the
case of K3 surfaces as a byproduct.
