Here are some facts about the day of superstition:
Its roots may be in Christianity.
Michael Bailey, a history professor at Iowa State University who specializes in the origins of superstitions, told USA Today in 2015 that ever since Jesus was crucified on a Friday, the day has been associated with "general ill omen."
Stuart Vyse, a psychology professor at Connecticut College, told USA Today that 13 guests are believed to have attended the Last Supper the night before Jesus was killed. The disciple who betrayed Jesus is believed to have been the 13th guest.
You're not more likely to go to the hospital.
A study published in World Journal of Surgery in 2011 found that there's no link between Friday the 13th and an increase of blood loss or the frequency of emergency room visits on that day.
"Our data indicate that such beliefs are myths far beyond reality," the study said.
Some people have a fear of the actual day when Friday falls on a month's 13th day.
Pope John Paul II was shot and nearly died on May 13, 1981.
There were 13 people at the Last Supper, and, in case you missed the first connection, it’s believed that Judas Iscariot - the disciple who betrayed Jesus Christ - was the 13th man to take his place at the table.
Jesus was crucified on a Friday.
A 13-year-old boy in England was struck by lightning on Friday the 13th at 1:13 p.m. (in military time, 13:13).
On Oct. 13, 1307, there was a mass arrest and execution of members of the Knights Templar. The Knights Templar or the Poor Fellow-Soldiers of Christ were anything but. Members were among the wealthiest and most powerful of Christian military orders. They are credited by many with establishing one of the earliest finance systems.
In not so Jolly Ol’ England, Friday was the traditional day for public hangings. Insult to injury – there were 13 steps up to the gallows, generally.
When it was lucky
The bus number 13 in London was never damaged during the blitz of the Second World War.
Apollo 13 was a 1970 NASA Moon mission famous for being a "successful failure." The accident that crippled the spacecraft happened on April 13.
It was on the jersey of Miami Dolphins Hall of Famer Dan Marino.
It was on the jersey of Los Angeles Lakers, and Philadelphia 76ers Hall of Famer Wilt Chamberlain.
A baker's dozen means you get 13 of something – or one more than a standard dozen. The down side is it is sometimes called a “Devil’s dozen.” (think donuts)
The visions of the Virgin of Fátima were said to have appeared on the 13th day of every month for six months in 1917.
It’s singer Taylor Swift’s lucky number.
Where 13 is not used
There’s no 13th floor in many high-rise buildings.
There is often no 13th floor in a hospital, and airports generally don’t have a Gate 13.
In triathlons, the number 13 is not used.
The number was not used in Formula One from 1977 to 2013.
While there are 19 counties in Norway they are numbered 1-20 because there is no number 13 county.
13 in general
Aluminum has the atomic number 13.
13 is the sixth prime number.
It is the smallest emirp or a prime number that is a different prime when its reversed - 31.
Fear of the number 13 is called Triskaidekaphobia.
Fear of Friday the 13th is Paraskevidekatriaphobia or, sometimes, Friggatriskaidekaphobia.
Fear of the number 17 – the number of letters in Triskaidekaphobia – is Heptadecaphobia.
The Aztecs considered thirteen a sacred number. It was the number that represented time. It stood for completion.
In Tarot, 13 is the card of “Death.” The card stands for transformation – ending something and starting something new.
There are 13 stripes on the American flag.
There are 13 stars in the Great Seal of the United States.