Friday the 13th is considered an unlucky day in Western superstition.
It occurs when the 13th day of the month in the Gregorian calendar falls on a Friday.
That happens at least once every year, but can occur up to three times in the same year.
In 2017, it occurred twice, on January 13 and October 13. In 2018, it also occurred twice, on April 13 and July 13.
There will be two Friday the 13ths every year until 2020; 2021 and 2022 will have just one occurrence each.
Fear of a particular date is called paraskevidekatriaphobia, fear for Friday 13 is called triskaidekaphobia.
One of the most popularised myths attempting to explain the origin of the Friday 13 superstition stems from events on Friday 13 October 1307, when hundreds of Knights Templar were arrested and burnt across France.
Mind your steps
It's Friday the 13th once again, and you might be planning on avoiding mirrors, ladders and walking over drains.
No 13th floor
In the Western world, some hotels will have no room 13, while a lot of tall buildings don’t have a 13th floor, jumping straight from 12 to 14.
The fear of Friday the 13th is so widespread that it’s even cheaper to travel by plane on the date.
In 1993 a British Medical Journal study claimed there was a “significant” increase in incidences on a Friday the 13, but the author of the study later confessed it was “a bit of fun” as traditional in the Christmas edition.
The Dutch Centre for Insurance Statistics on 12 June 2008 stated that "fewer accidents and reports of fire and theft occur when the 13th of the month falls on a Friday than on other Fridays, because people are preventatively more careful or just stay home.
Stay in bed, You said?
In 1976, New Yorker Daz Baxter was apparently so afraid of Friday the 13th he decided the safest place to stay was his bed.
Mr Baxter was killed when the floor of his apartment block collapsed that day.
Very superstitious, writings on the wall. Very superstitious, ladders 'bout to fall. Thirteenth month old baby, broke the looking glass. Seven years of bad luck, the good things in your past.
A black cat crossing your path signifies that the animal is going somewhere.
You never know what worse luck your bad luck has saved you from.