For the ease of explanation, I have to make some clarifications, $("h1") returns a JQuery object. There are bunch of methods that you could use in JQuery library such as .hide(), .remove(), .css() where you can do call it by $("h1").hide(). We call such methods as JQuery object method.

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. such as jQuery.trim(), jQuery.noConflict(),

JQuery defines one high-level object method and four high-level core method. These high-level methods are all based on the powerful low-level core method jQuery.ajax().

For your record, I did not invent the terminology JQuery object method or core JQuery method. I learned it from JQuery learning center.

Low-Level core JQuery method

  1. jQuery.ajax() or $.ajax()
  2. jQuery.ajaxPrefilter() or $.ajaxPrefilter()
  3. jQuery.ajaxSetup() or $.ajaxSetup()
  4. jQuery.ajaxTransport() or $.ajaxTransport()

High-Level core JQuery method

  1. JQuery.get() or $.get()
  2. or $.post()
  3. JQuery.getScript() or $.getScript()
  4. JQuery.getJSON() or $.getJSON()

High-Level JQuery object method

  1. .load()

We will first look at the high-level methods and then cover the low-level one especially jQuery.ajax(). In order to full understand the operation of the high-level methods, you'll need to understand jQuery.ajax(), even you might never need to use it explicitly.