After JWST, NASA's next flagship astrophysics mission is the ambitious Wide Field Infrared Survey Telescope, currently on track for a late 2025 launch. WFIRST will include the Coronagraph Instrument (CGI), which will be the first high-performance stellar coronagraph using active wavefront control for deep starlight suppression in space, providing unprecedented levels of contrast, spatial resolution, and sensitivity for astronomical observations in the optical. During its Technology Demonstration phase, CGI will resolve the signal of an exoplanet via photometry and spectroscopy and directly image and measure the polarization of disks. Future flagship mission concepts (e.g., HabEx and LUVOIR) aim to characterize Earth analogues with visible light flux ratios of ~10-10, and CGI is a critical intermediate step toward that goal, with predicted capability of ~10-9. Here, we present CGI's design and capability as well as some anticipated results from its technology demonstration.