explain z-index

Question

Can anyone please explain z-index property? I am not understanding it properly.

Answer 1

It can be understood as the layer depth number, which decides about the position of the object in the layer stack and its obscurity (or not). Of course, just visually :)

Answer 2

Which part confuses you?

z-index helps manipulate the contextual stacking order (how elements overlap each other)

https://css-tricks.com/almanac/properties/z/z-index/