Friday the 13th is recognised throughout the world as an unlucky day - although many people have no idea what the background to the superstition is.

The date itself represents the coming together of a pair of unlucky omens, the number 13 and the day of Friday itself.

The number 13 superstition travels back so far that it is shown in ancient Babylon's Code of Hammurabi, which dates back to 1772BC and carries no 13th law.

The end of the Mayan calendar's 13th Baktun is seen as the harbinger of the apocalypse, while some believe it is unlucky as it represents the 13 people who attended the Last Supper.

The fear of the number 13 itself is a recognised phobia (triskaidekaphobia) and a great number of tall buildings do not list a 13th floor, giving it a new title, such as 12a.

Friday's status as an unlucky day is thought to trace back to the Christian belief that Jesus was crucified on a Friday.

The connection between the number 13 and the day of Friday is not first documented until 1869, when journalist Henry Sutherland Edwards wrote a biography of composer Giochino Rossini.

"Rossini was surrounded to the last by admiring and affectionate friends; why Friday the 13th is unlucky," he wrote.

Author Thomas Lawson wrote a novel called "Friday the 13th" in 1907, revolving around an evil businessman's attempt to creash the stock market on the world's unluckiest day. The book was a success and later given a film adaptation.

The connection of both an unlucky day and an unlucky number has since become an iconic superstition, which the multi-million dollar Friday the 13th film franchise capitalised on, despite the film's plot concerning an invincible killer and seemingly having no connection to the date or even the concepts of luck and fate.

It seems the day's reputation as the unluckiest of the year will continue, with people being a touch more cautious each time it comes around, although it is not a regular occurence. Analysis of statistics showing previous occurences of Friday the 13 show that one will usually occur if the month starts on a Sunday.

Whether the day itself is actually unlucky will remain a matter of debate - although there is no harm in being a little careful on the unluckiest of days.