Can you explain purgatory and its significance in the Catholic faith?

Purgatory is a place in Catholic belief where souls undergo purification before entering heaven. It is seen as a temporary state of cleansing for those who have died in a state of grace but still have some remaining sins or imperfections. The significance of purgatory lies in the idea of God's mercy and justice, allowing souls to be purified and made ready for the perfection of heaven.