In case you haven't checked your calendar, today is — dun dun duh — Friday, the 13th! For few people, this date can actually mean good luck, but for many, it's associated with bad luck and misfortune. Historically speaking [1], that's because 13 is perceived as an unlucky number, and the sixth day of the week, Friday, is an unlucky day. It's the most widespread superstition in the US — some people won't leave their house, go to work, eat at a restaurant, get married, or fly on Friday the 13th. Many cities don't have a 13th street or avenue, and many buildings don't have a 13th floor. With all this said, are you superstitious about this day?

Source [2]