CDN – Content Delivery Network

Definition:

“A content delivery network or content distribution network (CDN) is a system of computers containing copies of data placed at various nodes of a network.” [1]

Example of CDN

Google Libraries API

Google Libraries API

The Libraries API is a content distribution network and loading architecture for the most popular, open-source JavaScript libraries.
http://code.google.com/intl/en/apis/libraries/devguide.html

For example the Jquery

jQuery UI
name: jqueryui
latest version: 1.8.12 (view older versions)
load request: google.load("jqueryui", "1.8.12");
extras: uncompressed:true (as in google.load("jqueryui", "1.8.12", {uncompressed:true});
path: https://ajax.googleapis.com/ajax/libs/jqueryui/1.8.12/jquery-ui.min.js
path(u): https://ajax.googleapis.com/ajax/libs/jqueryui/1.8.12/jquery-ui.js
site: http://jquery.com/
note: This library depends on jquery. You must also load jquery before loading this module. Version 1.8.3 is not hosted due to its short life, and the alias 1.8.3 actually loads 1.8.4.


Reference:

[1] http://en.wikipedia.org/wiki/Content_delivery_network