It all comes back to holly.
Red Christmas Ornament on Tree
Credit: Roberto Machado Noa / Contributor/ Getty Images

For as long as any of us can remember, red and green have been the colors associated with Christmas. But few people realize how these complementary hues came to represent the popular holiday.

According to Reader's Digest report, it actually started centuries ago with ancient Celtic people who revered red-and green-colored holly plants for surviving the winter. They believed that holly kept the Earth beautiful during the winter months, so they decorated their homes with it during Winter Solstice celebrations to bring protection and good luck to their families.

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Fast forward a few hundred years to when Haddon Sundblom, the illustrator behind Coca-Cola's iconic Santa Claus ads, burst onto the scene and forever solidified red and green as Christmas colors. To this day, people consider Sundblom's depiction of St. Nick to be "the real one." Before Coca-Cola's ads, Santa often appeared dressed in a variety of colors—a far cry from the signature red suit we associate with him now.