Boxing day was traditionally a day the servants had a day off from their duties. Because of this the gentry would eat cold cuts and have a buffet style feast prepared by the servants in advance. In modern times many families will still follow this tradition by eating a family style buffet lunch, with cold cuts rather than a full cooked meal. It is a time for family, parlour games and sports in the UK.
The traditional recorded celebration of Boxing Day has long included giving money and other gifts to those who were needy and in service positions. The European tradition has been dated to the Middle Ages, but the exact origin is unknown and there are some claims that it goes back to the late Roman/early Christian era; metal boxes were placed outside churches used to collect special offerings tied to the Feast of Saint Stephen.
In the United Kingdom it certainly became a custom of the nineteenth century Victorians for tradesmen to collect their “Christmas boxes” or gifts in return for good and reliable service throughout the year on the day after Christmas. The exact etymology of the term “Boxing” is unclear, with several competing theories, none of which are clearly true.
The establishment of Boxing Day as a defined public holiday under the legislation that created the UK’s Bank Holidays started the separation of ‘Boxing Day’ from the ‘Feast of St Stephen’ and today it is almost entirely a secular holiday with a tradition of shopping and post Christmas sales starting.- (Wikepedia)
Boxing day is celebrated in many countries, such as: England, Canada and South Africa. However, it is not observed in the United States.