jQuery
New Wave Javascript

jQuery uses a new concept to make the code short and simple. For those familiar with object-oriented programming, this concept should be rather straight-forward.

In a nutshell: Every method within jQuery returns the query object itself, allowing you to 'chain' upon it, for example:

$("p").addClass("test").show().html("foo");

Each of those individual methods (addClass, show, and html) each return the query object, allowing you to continue applying methods to the current set of elements.