Hmm..............................

From Wikipedia, calculus is the study of changes.

You will calculate differentials and integrals in calculus. You will see things like

$\frac{d}{dx}x^2=2x$

$\int_{0}^{\pi}sinxdx= 2$<--- seemed like I was wrong :P

$\int{2x^2}=\frac{2x^3}{3}$