jQuery is a cross-browser JavaScript library designed to simplify the client-side scripting of HTML. jQuery is free, open source software, dual-licensed under the MIT License and the GNU General Public License, Version 2.

jQuery's syntax is designed to make it easier to navigate a document, select DOM elements, create animations, handle events, and develop Ajax applications. jQuery also provides capabilities for developers to create plug-ins on top of the JavaScript library. This enables developers to create abstractions for low-level interaction and animation, advanced effects and high-level, theme-able widgets.

The modular approach to the jQuery framework allows the creation of powerful and dynamic web pages and web applications.

The jQuery library is a single JavaScript file, containing all of its common DOM, event, effects, and Ajax functions. It can be included within a web page by linking to a local copy, or to one of the many copies available from public servers (such as Google or Microsoft CDN).

<script type="text/javascript" src="jquery.js"></script>

The most popular and basic way to introduce a jQuery function is to use the .ready() function.

$(document).ready(function() { // jquery goes here });

or the shortcut

$(function() { // jquery goes here });