Stellar oscillations are powerful tools for understanding the structure and evolution of stars. With the advent of time domain space missions they can now be measured for large samples of evolved cool stars. The combination of this asteroseismic data, astrometry from Gaia, and large spectroscopic surveys is transforming our understanding of stellar populations and stellar physics. In this talk I review the current state of the art in red giant asteroseismology: both how well we can measure stellar properties using it and how it has changed our understanding of stellar populations and the theory of stellar structure and evolution. I will also discuss the powerful combination of asteroseismology and Gaia, providing two examples: testing the parallax zero point in Gaia with asteroseismology and testing asteroseismic scaling relations with Gaia.
