An "integral" is a fundamental concept in calculus, representing the accumulation of quantities. It can be thought of as the area under a curve on a graph, where the curve is defined by a function. Integrals help in calculating total values, such as distance, area, or volume, from rates of change. There are two main types of integrals: definite integrals and indefinite integrals. A definite integral has specific limits and results in a numerical value, while an indefinite integral represents a family of functions and includes a constant of integration. Both types are essential for solving various mathematical and real-world problems.