The Giant Magellan Telescope Integral-Field Spectrograph (GMTIFS) is a near-infrared imager and integral-field spectrograph, which will be the workhorse adaptive-optics (AO) instrument on the GMT when AO operations begin. We will describe the current design and proposed capabilities of the GMTIFS. We will also present a brief overview of GMTIFS science cases that include first-light objects, galaxy feedback and assembly, the nature of compact massive objects as well as the formation and evolution of stars and planets.