There is a term for a fear of the number 13 — triskaidekaphobia, of Greek origin. The term for a fear of Friday the 13th is paraskevidekatriaphobia.
Across many cultures, the belief that the number 13 is evil and brings bad luck is so strong that many hotels, office and apartment buildings do not have or recognize a 13th floor, airports usually do not have a 13th gate and many people stay home on Friday the 13th.
The Chinese and ancient Egyptians believed the number 13 brings good fortune. The Egyptians believed in 12 stages in life toward spiritual enlightenment. The 13th stage was the eternal afterlife. In this sense, death was not a place of fear, but a place of high regard for the afterlife.
One theory about why this negative belief about the number 13 exists is that Judas, who betrayed Jesus, was the 13th person to be seated at the Last Supper.
In 1881, a group of New Yorkers set out to debunk this and all other superstitions and formed a group called the Thirteen Club. Its first meeting took place on Friday the 13th at 8:13 pm and 13 people sat down to dinner in room number 13. To get into the room each guest walked under a ladder and sat down around piles of spilled salt. Needless to say, all of the guests survived. For the next 40 years, Thirteen Clubs cropped up all over the U.S., but then faded from popularity.
To find out about other superstitions, visit the Superstition Room.