The area of a circle refers to the amount of space enclosed by its circumference.
Pi (π): Pi is an irrational number that represents the ratio between a circle's circumference and its diameter. It's approximately 3.14159.
Sector Area: A sector area is part of a circle enclosed by two radii and an arc, similar to slicing up your pizza into smaller pieces.
Annulus: An annulus refers to the region between two concentric circles, like when you stack different-sized circular objects on top of each other.