What is the difference between `var`, `let`, and `const` in JavaScript?

Think of three types of containers. `var` is like writing on a whiteboard in the hallway — anyone walking by can see and change it, and it can be erased and rewritten freely. `let` is like a labelled box in a specific room — only code in that room can use it, and you can swap what's inside. `const` is a sealed box — you can still look inside and even rearrange items within it, but you can never swap the box itself for a different one.