What is "Purgatory"?

Purgatory is a belief in some Christian traditions that the souls of those who die in a state of grace, but still have some imperfections or sins to be purified, undergo a process of cleansing before they can enter heaven. Purgatory is not a place, but a condition or state of the soul that is different from the eternal punishment of the damned. Purgatory is based on the idea that nothing unclean can enter the presence of God, and that some souls need to be made ready for the joy of heaven by the grace of Christ.