It's "Pi Day" around the world.
March 14 commemorates the mathematical ratio used in figuring out equations involving circles.
A YouTube video from MathMovesU talks about how Pi is used every day.
Pi is named after a Greek letter.
Today is chosen because of the date 3-14, which coincides with the first three digits in "Pi."
Some people celebrate the day with actual pie, the tasty bakery treat.
Next year, geeks worldwide will celebrate as they're able to commemorate the date and time where the first ten digits of "Pi" will be in perfect order.
That will first happen on 3-14-15 at 9:26:53 a.m.
This year's "Pi Day" celebration is made all the more sweet by the fact that today is also Albert Einstein's birthday.