I thought Boxing Day was a British thing, not something recognized in "the whole world."
Australia, India, Sri Lanka, Malaysia, Myanmar (Burma), Seychelles, Maldives, Kenya, Singapore, an so forth (all British commonwealth members or possessions until after WWII) celebrate Boxing Day on December 26th. Boxing Day is an official day off for people that serve on Christmas. Early tradition had alms put in boxes at church services to be dispensed the next day (box-ing). Later, the tradition expanded to employers giving large bonuses and gifts to all employees.
The December 26th tsunami hit as hundreds of thousands gathered to the traditional celebrations of setting off fireworks and celebrating on the beaches throughout former or current British commonwealth nations.
As to your comment "the whole world" Once upon a time the British dominated the world. If they did not have a direct stake, they certainly controlled some aspect of trade or diplomacy. Britains ruled the oceans and almost all viable trade routes. Thus the British way of life was accepted as standard. Only three countries overthrew British dominion at their empire's height, the USA, the Republic of South Africa, and the Sully ancestral home in the Republic of Ireland.
Early tradition had alms put in boxes at church services to be dispensed the next day (box-ing). Later, the tradition expanded to employers giving large bonuses and gifts to all employees.Ah, now I know. I had wondered about the origins of Boxing Day. A Canadian professor once told us it was the day when unwanted Christmas presents were put back in their boxes to be returned to the store. I guess he was just pulling our legs!