Though sometimes it s easy to get lost in numbers or steps to take, the concepts weren t too terrible. However, Calculus is largely based on the concept of infinity. Obviously, its very hard to think of things as infinitely large or infinitely small. The discoverers of Calculus, however, were able to apply this concept of infinity to math. The comprehension of infinity is what makes Calculus difficult for many people, since it is what Calculus is based on.
Limits are where the concept of infinity comes into play.
Also using Calculus, you can graph almost any equation without having to plug it into a graphing calculator. Actually, they get it using Calculus. They look at a cone and they slice it into circles infinitely thin. They find the areas of each slice and then using Calculus, stack them up into a volume. When they use variables, they actually get the previous formula.