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: 
Both are quite difference. 

Basically you are using [Multiple Selector (“selector1, selector2, selectorN”)](http://api.jquery.com/multiple-selector/) in the following line. So its simple

```
$('#full-sized-content, #full-sized-area')

```

Where as in line you are using context based selector, Here you are selecting element with ID `full-sized-content` in childs of `$fullArea` 

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

```

is equivalent to 

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

```

Note As IDs must be unique in HTML you can simply use

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

```
```
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/)