Dialga presented the Gauntlet to the Time Lords of part of his gift to them which allowed them to control time and gain multiple lives. The Gauntlet was worn by Rassilon, ruler of the Time Lords, who quickly went mad with power and led the Time Lords into a war against the Daleks which devastated half of the Galaxy. Rassilon used the Gauntlet against both the Daleks and his own people, but eventually the Gauntlet locked its powers to him so he could use it only briefly.
When the Master re-wrote humanity to represent his image, the drum beat that symbolised his insanity was magnified by the six-million versions of the Master and Rassilon used the Gauntlet to lock on to that signal. The Master did not know this but Rassilon was actually the one who had implanted the drumming into the Master's head in the first place, as a backup plan. Rassilon used this signal to bring Gallifrey out of the Timelocked Time War and into the real world, just above Earth.
Rassilon used the Gauntlet to reverse the Master's meddling with humanity, and then attempted to kill the Doctor and the Master with it. However, the Doctor broke the link by destroying the machinery holding Gallifrey in place, and it was soon sucked back into the Time War. The Master assaulted Rassilon and the Gauntlet would not protect him, and soon they were both trapped in the Time War forever.
After the Time War ended, the Gauntlet was recovered from the ashes of Gallifrey by the Doctor and stored in his TARDIS. Its functions after that, if any, are unknown.