Calculus is the mathematical study of continuous change, primarily divided into differential and integral calculus. It provides the essential framework for modeling dynamic systems, optimizing functions, and understanding the physical world, making it indispensable in physics, engineering, and data science. Mastering the relationship between derivatives and integrals—as formalized by the Fundamental Theorem—transforms calculus from rote memorization into a unified computational system for analyzing rates of change and accumulation.