jQuery is a JavaScript library designed to simplify HTML DOM tree traversal and manipulation, as well as event handling, CSS animation, and Ajax. Wikipedia

A lightweight JavaScript library that emphasizes interaction between JavaScript and HTML Wikipedia Disambiguation

JavaScript library Wikidata

A JavaScript library with predefined functions which simplify many common tasks done with JavaScript and enable them to function regardless of the web browser on which they are executed, using CSS selectors to query HTML elements on a web page and manipulate them. Wiktionary