[jQuery] What is $.data?

[Adam Walters]

Hello,

I'm looking through and tracking the code for a jQuery autocomplete
plugin (found here: http://reinh.com/2008/1/7/new-jquery-autocomplete-plugin
)

I'm trying to get my JSON data to appear properly, and getting close,
however, i keep coming across $.data...for example:

$.data(document.body, "autocompleteMode", false);

Could somebody tell me what $.data is and what it's purpose is?
Perhaps point me to soem resources?  i can't seem to find anything.

Thanks!
Adam