The EXIST mission will transform the way that gamma-ray bursts (GRBs) are studied and the ways in which the universe will be probed. Here, we review the EXIST ``GRBs a probes’’ science objectives in light of recent discoveries. EXIST will not only discover dozens of z ¿ 7 GRBs but obtain the necessary followup onboard -with the X-ray imager and optical-IR imaging spectrograph -to probe the nature of metal enrichment in nascent galaxies and the reionization history of the universe.