“Each object contains a reference to the object it was derived from”
The prototype property is a reference. Our Accountant object’s prototype contains a reference to the Person prototype. This has two very important implications. Firstly, if a change is made to a prototype, all objects with that prototype get the same change. If we have 2 Accountant objects that we made from our Accountant prototype, and we add an “age” property to the prototype then both Accountant objects will have an accessible age property.