  Binary systems anchor many of the fundamental relations relied upon in
asteroseismology. Masses and radii are rarely constrained better than when
measured via orbital dynamics and eclipse depths. Pulsating binaries have much
to offer. They are clocks, moving in space, that encode orbital motion in the
Doppler-shifted pulsation frequencies. They offer twice the opportunity to
obtain an asteroseismic age, which is then applicable to both stars. They
enable comparative asteroseismology -- the study of two stars by their
pulsation properties, whose only fundamental differences are the mass and
rotation rates with which they were born. In eccentric binaries, oscillations
can be excited tidally, informing our knowledge of tidal dissipation and
resonant frequency locking. Eclipsing binaries offer benchmarks against which
the asteroseismic scaling relations can be tested. We review these themes in
light of both observational and theoretical developments recently made possible
by space-based photometry.
