  In this review we discuss emergence of unimodular gravity (or, more
precisely, Weyl transverse gravity) from thermodynamics of spacetime. By
analyzing three different ways to obtain gravitational equations of motion by
thermodynamic arguments, we show that the results point to unimodular rather
than fully diffeomorphism invariant theories and that this is true even for
modified gravity. The unimodular character of dynamics is especially evident
from the status of cosmological constant and energy-momentum conservation.
