What is the purpose and basis of the stigmata? The stigmata is sores or wounds in the places that Jesus suffered wounds during the crucifixion. That's about as much as I know.

My questions, to be answered from a Catholic perspective:


What's the purpose of the stigmata?
What is the Biblical basis, if any, for the stigmata?
How does the stigmata not indicate Christ's suffering was insufficient?
How do we know that the stigmata reflects Christ's crucifixion and not someone else that was crucified?
Stigmata is a grace given to a follower of Christ₁, meaning
Stigmata is not public revelation, nor could it be. So it's not biblical in the way the 7 Sacraments (Baptism, Marriage, the Eucharist, Reconciliation, Holy Orders, Last Rites and Confirmation) are.
These private revelations often come directly from Christ Himself.  It is contingent on the authority of the Church ₂ to quash belief in a particular private revelation or allow it to continue.


₁ do all work miracles? (1 Cor 12:29)

₂ thou art peter (Matt 16:18))