Calculus is a branch of mathematics that studies continuous change. It is divided into two main parts:

1. **Differential Calculus**: This focuses on the concept of a derivative, which represents the rate of change of a function. It involves finding the slope of a curve at any point and solving problems related to rates of change.

2. **Integral Calculus**: This deals with the concept of an integral, which represents the accumulation of quantities, such as areas under a curve. It involves finding the total size or value, such as the area under a graph of a function.

Calculus has numerous applications in science, engineering, economics, and other fields, providing tools for modeling and solving real-world problems.