This is a system plugin for Joomla. It allows you to load a jQuery on your site easily and helps you to resolve all conflict with mootools with Joomla.
1. Install the plugin.
2. Go to plugin configuration and select the jQuery version, Turn On/Off the "Remove Mootools Conflict" option.
3. Enable the plugin and save.
Then enjoy to use any jQuery script on your site.
Note: this plugin add jQuery on top of your head tag, so you do not need to install any other jQuery plugin in your site anymore.