In what way does it break down? Maybe if one is thinking of boxes, going by "a change to the value of a"? The book says:

> When a binding points at a value, that does not mean it is tied to that value forever. The = operator can be used at any time on existing bindings to disconnect them from their current value and have them point to a new one

In this case:

    let a = 22;

The binding a points to the value 22.

    let b = a;

The binding b points to the same value that a points to, namely 22.

    a = 23;

The binding a now points to a different value 23. The binding b is not affected.

I've linked it a few times in this thread, but see the equivalent article for Python, which explains it clearly: https://nedbatchelder.com/text/names1.html

(It cannot break down because it's how the language works.)

You're struggling due to a conflation of two concepts.

Binding refers to associating a name with a value. Assignment is a case of binding, but not the only one; two other examples are positional arguments in a function signature, and ESM imports. A binding can be mutable (let assignment, function arguments) or immutable (const assignment, ESM import).

Value mutability is orthogonal. You can mutably bind a primitive value as "let a = 22" and then mutate the binding via reassignment, but you can't mutate the value itself; you can immutably bind a reference value as "const b = {}" and mutate the referenced object via property access, but you can't mutate the binding.

I refer to bindings all the time, where it's useful to be clear in meaning. I also make sure to introduce the concept to mentees who aren't already familiar with it, and by all reports thus far it's proven as valuable an abstraction for them as it did for me when I first learned of it.