Infinitesimal calculus

Infinitesimal calculus is a branch of mathematics that studies how things change and accumulate. It introduces the idea of infinitesimally small quantities—values so tiny that they are almost zero but not quite—to analyze how a function's output varies with tiny changes in input. This allows us to find rates of change (derivatives) and total amounts accumulated (integrals). These tools are essential for understanding curves, motion, growth, and many natural phenomena, providing precise methods to analyze continuous change in science, engineering, and beyond.