"The Eternal Ratio of Diameter and Circumference"
Pi (π) is the ratio of a circle's circumference to its diameter. It begins 3.14159... but never ends and never repeats. It is an irrational and transcendental number. From ancient Egypt to modern supercomputers, humans have been obsessed with calculating its digits.
Archimedes approximated Pi by drawing polygons inside and outside a circle. By increasing the number of sides (up to 96), he narrowed down the value. This was an early form of calculus (limits). Today, computers have calculated Pi to over 100 trillion digits.
Pi is not just for circles. It appears in the meandering of rivers, the double helix of DNA, the pupil of the eye, and even in probability theory (Buffon's Needle). It is a fundamental constant woven into the fabric of the universe.