The stigmata are marks that replicate the wounds that Christ received at his crucifixion on his hands, feet and side. Certain Christian saints (for example, Saint Francis of Assisi) are believed to have miraculously received the stigmata as marks of piety.
Giotto. St. Francis Receiving the Stigmata. Fresco. Upper Basilica of St. Francis, Assisi, Italy. 1297-1300.