jQuery.com In Their Own Words
The core of the library revolves around different mouse interactions, namely drag and dropping, sorting, selecting, and resizing.
On top of the core interactions are built a number of reusable widgets, including accordions, date pickers, dialogs, sliders, table sorters, and tabs.
Finally, the library is finished off with a few effects that you can use to liven up your site, specifically magnifier and shadow.”
Why jQuery.com It Might Be A Killer
jQuery is flexible enough for a wide range of interests. It also simplifies matters quite a bit, making it possible for users to concentrate on more pressing tasks.