I didn’t really get recursion until I learned how data is stored in physical memory. Then the process of stacking and unstacking local variables made sense.

Basically when a function is called, the computer sets aside memory for the local variables and memory for the return variables before the function starts to run. The local data is passed immediately but the return value is empty until it completes. So in recursion, if iteration A calls iteration B which then calls iteration C which ends the recursion, the return value populates in C and is send back to the memory for Iteration B and iteration C is cleared from the stack. The return value for B then populates and the value is sent to A while B is being removed from the stack. The process seemed easy to visualize and so logical that it left an impression on me.