I'm taking a short Calculus session this summer and the teacher zooms through things. I still don't fully understand differentials. I know that derivative give you the slope of a function at any point. And I know that dy is a small change in y and dx is a small change in x and how they can be used to approximate things. But is that all there is to it? The fact that dy is a small change in y and dx is small change in y? I noticed that they're used in integrals(we just started learning about them) when referring to what we're integrating with respect to. Why did we use dy/dx is derivative but dx in integrals? Thank you.