3Blue1Brown is a YouTube channel that produces terrific computer-animated explanations of various mathematical concepts. If you have twenty minutes free some time, I highly encourage you to take a look at some of the videos below, which give a nice visual introduction to several concepts in calculus.

The Essence of Calculus

The Paradox of the Derivative

Derivative Formulas through Geometry

Visualizing the Chain Rule

Implicit Differentiation: What’s Going On Here?

Limits

Higher-Order Derivatives