jQuery
jQuery is a popular cross-platform JavaScript library that can help web developers perform document traversal and manipulation, event handling, animation, Ajax, applying styles, and more.
jQuery has become the most popular JavaScript library on the web. It's designed to make it easier to navigate a document, select DOM elements, create animations, handle events, and develop Ajax applications.
jQuery is free, open-source software licensed under the MIT License.
jQuery Tutorial
Learn all about jQuery with this jQuery tutorial: