What is Purgatory?
Purgatory is state of purification, the final stage of pardon for sins.
     "Purgatory (Lat., "purgare", to make clean, to purify) in accordance with Catholic teaching is a place or condition of temporal punishment for those who, departing this life in God's grace, are, not entirely free from venial faults, or have not fully paid the satisfaction due to their transgressions."
The Church has always taught the doctrine of purgatory. Purgatory is a temporal punishment due to sin after death.
                                                                                 http://www.newadvent.org/cathen/12575a.htm