Pi Day is a non-religious holiday celebrating the number pi. It is celebrated on March 14 (3/14 in month/day format), which looks like the first 3 numbers of Pi, 3.14.
Creation
It was created in 1988 by Larry Shaw. It is mainly held at San Francisco Exploratorium, where Shaw worked as a physicist.
Celebration
There are many ways to celebrate Pi day. Some people eat Pi Pie and discuss the relevance of Pi. Schools celebrate by putting up decorations or giving students Pi-Related Math Problems. Some Schools also put Math Night on this day as a token to Pi.