$ vs $()

Until now, we've been dealing entirely with methods that are called on a jQuery object. For example:

$( "h1" ).remove();

Most jQuery methods are called on jQuery objects as shown above; these methods are said to be part of the $.fn namespace, or the "jQuery prototype," and are best thought of as jQuery object methods.

However, there are several methods that do not act on a selection; these methods are said to be part of the jQuery namespace, and are best thought of as core jQuery methods.

This distinction can be incredibly confusing to new jQuery users. Here's what you need to remember:

• Methods called on jQuery selections are in the $.fn namespace, and automatically receive and return the selection as this.
• Methods in the $ namespace are generally utility-type methods, and do not work with selections; they are not automatically passed any arguments, and their return value will vary.

There are a few cases where object methods and core methods have the same names, such as $.each() and .each(). In these cases, be extremely careful when reading the documentation that you are exploring the correct method.

In this guide, if a method can be called on a jQuery selection, we'll refer to it just by its name: .each(). If it is a utility method -- that is, a method that isn't called on a selection -- we'll refer to it explicitly as a method in the jQuery namespace: $.each().