The symbol π (pi) represents a mathematical constant that is the ratio of a circle's circumference to its diameter. It is approximately equal to 3.14159, though it is an irrational number, meaning it cannot be expressed as an exact fraction and its decimal expansion goes on forever without repeating.

Pi is widely used in geometry, trigonometry, and calculus, and plays a critical role in the formulas for the area and circumference of a circle:

• Circumference of a circle: $C = 2\pi r$, where $r$ is the radius of the circle.
• Area of a circle: $A = \pi r^2$.

Would you like to explore more about pi in a particular context or need a deeper explanation of how it's used in different fields?

Related Questions:

1. How do you calculate the area of a circle using pi?
2. What are some other irrational numbers similar to pi?
3. How did pi first come to be discovered in history?
4. How is pi used in calculus, particularly in integrals?
5. What are some interesting approximations for pi in mathematics?

Tip: You can calculate the value of pi more accurately by using infinite series, like the Leibniz series or Nilakantha series.