How do var, let, and const differ in scoping and hoisting behavior, what is the temporal dead zone, and how does the engine set up scopes before execution?

Imagine you have different boxes for your toys. 'var' is like a box that stays in the big playroom (function), even if you put it in a smaller corner (block). 'let' and 'const' are like boxes that stay exactly where you put them, in that corner. The 'temporal dead zone' is like a rule that says you can't touch a 'let' or 'const' box until you've actually placed it there, even if you know it's coming.