Gallifrey was duplicated eight times to create the Nine Gallifreys. It was used both to confound its enemies and as a place of refuge. Gallifrey was still destroyed by the Eighth Doctor (following involvement from Faction Paradox) during the Second War in Heaven. It was later recreated.
On the final day of the Time War, the Time Lords, now led by Rassilon, broke the time lock to materialise Gallifrey in Earth's skies in 2009, thinking the Doctor would precipitate their ultimate demise on that final day through the Moment. However, the Tenth Doctor sent the planet, Time Lords included, back to its doomed fate, by breaking the link that brought the Time Lords to Earth.
Gallifrey was thought to have been destroyed by the Doctor in the Time War, but was frozen in time in a pocket dimension by the first thirteen incarnations of the Doctor. The vast majority of the Daleks died in the crossfire when Gallifrey disappeared.