  The Shapiro effect, also known as the gravitational time delay, is close kin
to the gravitational deflection of light that was the central topic of our
Summer School. It is also an interesting test bed for exploring a topic that
provides the foundations for most of the calculations we have done in this
school, yet is highly complex when treated more rigorously: the question of the
Newtonian limit, and of the post-Newtonian corrections that must be applied to
include the leading-order effects of general relativity. This contribution
discusses simplified derivations for the gravitational redshift and the Shapiro
effect, as well as astrophysical situations in which the Shapiro effect can be
measured.
