I know that:
1) Change in $x$ ie., $Δx$, when $\lim Δx→0$, then $Δx$ is replaced by $dx$.
2) I also know that $∂x$ is used in partial derivative.
Then what is $δx$? Is $dx$ and $δx$ is just the same or something different. I want some mathematical explanation.
Generally, I've seen "$\delta x$" to mean a tiny change in $x$, without necessarily invoking all of the mathematical machinery of a derivative. In a derivation, you might start with variables $ \delta x $ and $\delta t$ as ordinary quantities, and then later put in an explicit step that takes the limits as they approach $0$.
