JQuery

Overview
jQuery is a JavaScript library with tons of timesaving and fantastic features.  In a nutshell jQuery can make your life easier with:
- Browser friendly DOM navigation
- Browser friendly animations
- advanced techniques for doing just about anything you do with JavaScript - but in a nice and neat library.

Latest Version
You can get the latest version here:  http://jquery.com/

Sweet Tutorials
I love http://tympanus.net/codrops/.  You could spend an entire evening entertaining yourself going through the tons of tutorials and samples of what jQuery can do. 

The Gotcha
As with any tutorial, sample, example, or implementation - things change.  Sometimes the changes in jQuery just cause problems.  So pay attention to the version of jQuery you are using.