jQuery event namespaces allow you to separate event listeners.

// bind click listeners
$element.on( 'click.alpha', function() {
  console.log('Alpha click');
});
$element.on( 'click.beta', function() {
  console.log('Beta click');
});
// unbind alpha click listener only
$element.off('click.alpha');

EDIT The rest of this post is false I had thought I verified this, but alas, no. Triggering with a namespace will not trigger that event without the namespace.

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They can also be used when triggering events, to specify where that event came from.

$element.trigger('click.pluginName')

I’m using namespace triggering in Flickity, as a way to distinguish Flickity’s select event from the native select event.

// create jQuery event from original event object
var $event = jQuery.Event( event );
// set type, like select.flickity
$event.type = type + '.flickity';
this.$element.trigger( $event, args );