Certainly! The concept of definite and indefinite integrals is fundamental in mathematics and has various real-world applications. Definite integrals, as you mentioned, are used to find the "area under a curve" and play a crucial role in calculus, physics, and engineering. For instance, in physics, they help calculate quantities like displacement, velocity, and acceleration.
Maxwell's electromagnetism equations, part of the field of electromagnetism, also rely on integral calculus for solving complex problems related to electric and magnetic fields. This shows the wide-reaching impact of integrals in understanding the behavior of our physical world.
Regarding their discovery and use, integral calculus was developed over centuries by mathematicians like Newton and Leibniz, who independently developed the fundamental theorems of calculus. They devised these concepts to solve problems in physics and mathematics.
In essence, the discovery and application of integrals are the result of centuries of mathematical development driven by the need to understand and solve real-world problems in various fields, making them indispensable tools in science and engineering today.