  This article surveys the development of observational understanding of the
interior rotation of the Sun and its temporal variation over approximately
forty years, starting with the 1960s attempts to determine the solar core
rotation from oblateness and proceeding through the development of
helioseismology to the detailed modern picture of the internal rotation deduced
from continuous helioseismic observations during solar cycle 23. After
introducing some basic helioseismic concepts, it covers, in turn, the rotation
of the core and radiative interior, the "tachocline" shear layer at the base of
the convection zone, the differential rotation in the convection zone, the
near-surface shear, the pattern of migrating zonal flows known as the torsional
oscillation, and the possible temporal variations at the bottom of the
convection zone. For each area, the article also briefly explores the
relationship between observations and models.
