While Santa’s street remains a mystery, at least we know his address ends in H0H 0H0. And that’s not actually a joke. It’s a Canadian postal code, which has six characters and a mix of letters and numbers. It seems that the lack of a standardized address for the jolly old elf resulted in countless numbers of children’s letters going undelivered. To solve that problem, the Canadian postal service created Santa’s own, personal ZIP code. In the decades since, millions of children have used it to mail letters to Santa in dozens of languages, and have received personalized replies in return in (with an assist from some of St. Nick’s countless postal volunteers).