By @samuel · 2021-10-02 17:11
It's not! That's just the last element you clicked on.
It's like right clicking an element in the Elements tab and selecting "Store as a global variable", except you can save those clicks if you just need to work with the last element.
$0 is the last one,
$1 is the previous one,
$2 is the one selected before the previous one, etc.