Question: I know this isn't a code issue related question, but it's something I'd love to know and it may help others:

What's the difference between using this:

```
$(function() {
    var $fullArea = $('#full-sized-area');
    var $fullContent = $('#full-sized-content', $fullArea);
});

```

Over say this:

```
$(function() {
    var $fullArea = $('#full-sized-area');
    var $fullContent = $('#full-sized-content, #full-sized-area');
});

```

Answer: 
There is a difference,

**[Demo : Multiple selector](http://jsfiddle.net/93k2t/)**

```
var $fullContent = $('#full-sized-content, #full-sized-area');

```

Selects both the elements - **[Multiple selector](http://api.jquery.com/multiple-selector/)**: `$('#elem1,#elem2,...')`

---

**[Demo: Parent-child](http://jsfiddle.net/93k2t/1/)**

```
var $fullContent = $('#full-sized-content', $fullArea);

```

In this case : `#full-sized-content` has to the child of `#full-sized-area`

So its is equivalent to 

```
$('#full-sized-area #full-sized-content');
          Parent          Child                

```
```
var $fullContent = $('#full-sized-content', $fullArea);

```

The above actually a context based selector. So, what is does in simple manner is:-

```
$fullArea                           // get the fullArea element
    .find('#full-sized-content')    // find all the descendants with this id inside it

```

While the code below means:

```
// Get both the elements with id full-sized-content & full-sized-area
var $fullContent = $('#full-sized-content, #full-sized-area');

```

It's like a combined selector. So, if you do the below thing for 1st code:-

```
$fullContent.css('color', 'red');

```

It will only make the color red for the element `#full-sized-content` inside `$fullArea`
Whereas if you use the same code for the 2nd part, it will color both the `full-sized-content` & `full-sized-area` elements.

[**FIDDLE DEMO**](http://jsfiddle.net/Lw4Qa/)