What are the prerequisites for calculus? I've studied basic math a very long time ago and would like to start over. I remember studying derivatives, but never really understood what rates of change were. I would like to know calculus, differential equations, dynamical systems. What information should I begin studying? should I know in depth about ratios, proportions, rates of change? I'm not very confident on these, especially rates of change. Should I begin by refreshing over this material? can anyone please also recommend any introductory material regarding these that I could start from. Thank you.

A strong foundation in algebra Is very important, as most if not all of calculus relies on the idea of a function, something that is covered very in-depth in algebra 1 and 2. For example, the pre-calculus course at my school covers: polynomials, sketching graphs, trigonometry, and exponential and logarithmic functions. Another topic that I would recommend covering but isn't necessary is limits, as they are the foundation to all of calculus, but most textbooks and courses spend the first few chapters discussing them. 
One great textbook I found useful was this Calc 1 textbook. However, learning math from just a textbook can be difficult, especially Calculus, because it introduces so many new subjects, so you might find 3Blue1Brown's Essence of Calculus youtube videos helpful. 
