  After a quick review of the wild structure of the complex moduli space of
Calabi-Yau threefolds and the role of geometric transitions in this context
(the Calabi-Yau web) the concept of "deformation equivalence" for geometric
transitions is introduced to understand the arrows of the Gross-Reid Calabi-Yau
web as deformation-equivalence classes of geometric transitions. Then the focus
will be on some results and suitable examples to understand under which
conditions it is possible to get "simple" geometric transitions, which are
almost the only well-understood geometric transitions both in mathematics and
in physics.
