Photo credit: gardenofeaden.blogspot.co.uk
The other day my husband asked me whether I knew why Boxing day was called Boxing day and I had to admit that I didn’t. Somehow I never asked myself this question. So I went on a googling mission and found an article in Time that was quite helpful.
In fact, the origin of Boxing day is somewhat murky. One possible explanation is that around Christmas people were encouraged to donate money to the poor, putting them in alms boxes. According to another popular version, the aristocracy distributed presents (boxes) to their servants, who ‘returned home, opened their boxes and had a second Christmas on what became known as Boxing Day.’
It’s impossible to say which one (if any) is correct and in any case, these days Boxing day is mostly known as the Day When the Sales Start.
Confessions of the Linguistic Spy 