calculus

Calculus is the mathematical study of continuous change, and the principal precursor of modern mathematical analysis. Originally called infinitesimal calculus or the calculus of infinitesimals, it has two major branches, differential calculus and integral calculus. Differential calculus analyses instantaneous rates of change and the slopes of curves; integral calculus analyses accumulation of quantities and areas under or between curves. These two branches are related to each other by the fundamental theorem of calculus. Calculus uses convergence of infinite sequences and infinite series to a well-defined mathematical limit.

Calculus is the "mathematical backbone" for solving problems in which variable quantities change with time or another reference value. It has also been called "the basic instrument of physical science".