Space missions have uncovered a rich, and high amplitude, pulsation spectrum in red giant stars. The information encoded in the pulsation frequencies is transforming our understanding of stars. At one level, crucial information (such as mass, radius, and age) can be used for stellar population studies. At another, we can make critical tests of stellar physics with new seismic observables (such as core rotation, convection zone depth, and core mass.) In this talk I begin by reviewing the pulsation properties of giants. I’ll then cover the likely cause of the observed frequency patterns, highlighting the role of strong coupling between core g-modes and envelope p-modes. I will then discuss two crucial findings: the ability to distinguish giants with and without core He burning by pulsation properties alone, and the discovery of rapid core rotation in red giants. Finally, I’ll use seismic data from the open cluster NGC 6791 to argue for the validity of seismic mass and radius estimates and to measure mass loss between the red giant branch and the red clump. The implications of these findings will be briefly discussed.