Why Is the Day After Christmas Known as Boxing Day in the United Kingdom?

What is Boxing Day? Mark Connelly, a professor of modern British history at the University of Kent, told Inside Edition Digital, “It's part of the ancient Christian calendar, marking the first great martyr of Christianity, St. Stephen.” His feast day in late December became a time of charitable giving -- particularly from the rich to the poor. “It was quite literally the day of boxes. Little boxes of alms, church doles, little boxes of coins would usually be given out.”