I think anyone with a decent Internet connection and a passing knowledge of mathematics knows that today - 3.14 - is Pi Day.
But, have you ever stopped to think what pi - the number, not the letter in the Greek alphabet - really is? Well, this math major can tell you! Put simply, it's a constant number, equal to the ratio of a circle's circumference to its diameter. A circle is a funny shape - every point on it is equidistant from the center, so a constant like this is possible.
And since we're talking about circles, I think it is appropriate to use the greatest song ever written about this cool shape!