Calculus is a branch of mathematics that focuses on the study of change and motion. It provides tools for understanding how quantities vary and allows us to calculate rates of change, such as speed, and areas under curves. Key concepts include limits, derivatives, and integrals, which are essential for solving problems in physics, engineering, and economics. The two main branches of calculus are differential calculus, which deals with the concept of the derivative, and integral calculus, which focuses on the accumulation of quantities. Together, they form a powerful framework for modeling and analyzing dynamic systems in various fields.