jquery this versus $(this) and maybe even $this
<p>I often see examples of using the keyword <code>this</code> in jquery.  Sometimes I see it used with the $ and parenthesis, other times without. And I thought I saw it used with a little of each.</p>

<p>So,</p>

<pre><code> var id = this.attr('id');

 var id = $(this).attr('id');

 var id = $this.attr('id');
</code></pre>

<p>Are these all the same? Is there a preferred way?  Is <code>this</code> a javascript thing and <code>$(this)</code> a jQuery thing? If so, where does <code>$this</code> fall?</p>

<p>I know this is probably a total newbie question, but I haven't been able to get the simple, <code>this</code>, by itself, to work. I can only get <code>$(this)</code> to work.  I'm not sure if I'm doing something wrong, or if I've been reading examples with typos.</p>
