Linked List fundamental concepts
This has nothing to do with linked lists and everything to do with references (see also pointers). When you assign a mutable object to a variable, the variable holds a reference to the actual object: its memory address. If you assign the same object to two different variables, they both reference the same object; both variables internally hold the same memory address (and changing its members will change the underlying object). But when you then reassign one of those variables, that one now points to a different object again.