March 14 marks Pi Day, the annual celebration of the mathematical sign and number π. In mathematics, as most know, the symbol is used to represent the constant that links together the circumference and the diameter of a circle. The most common approximation is 3.14 (hence the date of 3/14, following the month/day date format) or, even more precisely, 3.14159; being an irrational number, however, π continues infinitely and without any pattern beyond its decimal point.
The first celebration of Pi Day was held in 1988 at the San Francisco Exploratorium, an interactive science museum, and was organized by physicist Larry Shaw. The initiative soon developed into a popular "geek" phenomenon and Pi Day is now one of the internet's most beloved "festivities".
Coincidentally, one of the most influential scientists of all time was born exactly on Pi Day: we're talking about Albert Einstein, who was born on March 14, 1879!
"Initial B", illumination from the manuscript "Derivationes", ms. 0428 (0912), f. 022v, 1270, Musée Condé, Chantilly.