jQuery is the most popular javascript library in the world, many of developers are using it, because it`s a lightweight、easy to use and learn library, you can see it everywhere when you suffing the internet.
Here are some useful links that shows you examples about jQuery and jQuery UIand jQuery Flot.
If you are an experienced developoer and new to know jQuery, you`ll love
it immediately, because jQuery has a bunch of powerful element selectors
, for example you can select elements by it`s tag like <p> or <div>, or you can select elements by class selector, these selectors allows you to select mutiple elements that has same css class name or same html tag.
jQuery aslo built in useful Ajax functions, allows you to perform Asynchronous HTTP request in just a few lines of codes, you can also get ruturned json format result by using getJSON() , in a nutshell, jQuery is a must-have for every developers.