JS simply means Javascript by the way var, let, and const are all keywords used for declaring variables in JavaScript, but they differ in terms of scope, reassignment, and immutability. var are function-scoped or globally-scoped, which means they are accessible within the function they are declared in, or globally if declared outside a function. let allows for block-scoped variable declaration. Variables declared with let are limited in scope to the block, statement, or expression in which th...