Purgatory (Latin: purgatorium, borrowed into English via Anglo-Norman and Old French) is a belief in Catholic theology. It is a passing intermediate state after physical death for purifying or purging a soul before entering Heaven. A common analogy is dross being removed from gold in a furnace.

In Catholic doctrine, purgatory refers to the final cleansing of those who died in the State of Grace, and leaves in them only "the holiness necessary to enter the joy of heaven"; it is entirely different from the punishment of the damned and is not related to the forgiveness of sins for salvation. A forgiven person can be freed from his "unhealthy attachment to creatures" by fervent charity in this world, and otherwise by the non-vindictive "temporal (i.e. non-eternal) punishment" of purgatory. [wikipedia]

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Dante
"After their journey through Hell, Dante and his guide Virgil arrive at the foot of Mount Purgatory — the place where souls are cleansed of their sins before entering Heaven.
Before them stand the gates of Purgatory, guarded by an angel.
"…Upon this the Angel of God held both his feet, seated upon the threshold …
Devoutly I threw myself at the holy feet; I besought for mercy’s sake … But first upon my breast I struck three times. Seven P’s upon my forehead he inscribed with the point of his sword, and “See that thou wash these wounds, when thou shalt be within,” he said."
[Divine Comedy. Dante. Bodleian Library MS. Holkham misc. 48, 14th century]