MooTools (which stands for My Object-Oriented "JavaScript" Tools) is a lightweight, modular, object-oriented JavaScript framework. It greatly speeds up and enhances the development cycle of feature-rich Ajax/JavaScript web applications. Created by Valerio Proietti—who originally intended it to be an extension to the Prototype JavaScript framework—MooTools has since grown into an independent, open-source, and very robust JavaScript framework with a solid team of core developers and thousands of users who support, contribute, and rabidly evangelize the project.

MooTools, in essence, abstracts normal JavaScript code so that you can write more terse and elegant client-side scripts. It has a host of useful functions, methods, and classes that'll let you develop robust web components and web applications.

The developers of MooTools strongly believe in applying Object-Oriented Programming (OOP) principles to JavaScript, a structural programming language. Since everything in JavaScript is an object, MooTools provides a cleaner, easier, and more elegant way to manipulate the object to our will. MooTools also helps make the JavaScript code cross-browser compatible.