Question: If for instance we copy an object like this and modify a property in our copied object:

```
let user = { name: 'John' };

let admin = user;

admin.name = 'Pete'; // changed by the "admin" reference

alert(user.name); // 'Pete', changes are seen from the "user" reference

```

Why does: 

```
let user = { name: 'John' };
let admin = user;
user = null;
console.log(user); // will return null
console.log(admin);// will return {name: "John"}

```

Answer: 
By calling `user = null`, you're destroying the reference that the existing Object had to the variable called `user`, not the actual Object.

You'll be able to use the Object as long as there exists some reference to it. When there is no more references, it'll be garbage collected eventually.

Visualisation of what you did:

```
user --> { name: 'John' }

user --> { name: 'John' } <-- admin

user --> null
         { name: 'John' } <-- admin

```
First of all: that is not garbage collection, but I will not dwell on that since that's not your actual question.

In memory the space occupied by the object `{ name: 'John' }` is still storing that.

You just assigned `null` to one of the variables "pointing to it".

Imagine it as *pointers* like in c++:

`let user = { name: 'John' };`

```
 user ⟶ {name: 'John'}

admin    

```

`let admin = user;`

```
 user ⟶ {name: 'John'}
       ↗
admin 

```

`user = null;`

```
 user    {name: 'John'}
       ↗
admin 

```

And therefore "user" isn't really pointing to anything, it's pointing to the '**null**' point that basically means '*nothing*'.