title: What's the difference between jQuery.data and jQuery._data ( underscore data )?
body: <p>While going through the source, I noticed that 'toggle' supposedly uses <code>jQuery._data</code> to store the state of the element. I examined the <code>jQuery.cache</code> object in chrome and found that the element's data object had yet another object under it prepended by the word jQuery with a number that I'm guessing uniquely identifies it. However, I saw no data regarding the state of the element. Simply <code>{olddisplay: 'block'}</code>. Any clues as to the purpose of jQuery._data and how it works per se?</p>
  
  <p>I've been staring at the source all day .... please don't tell me to view the source. My eyes and brain will thank you.</p>