Before we have any major discussion about jQuery it is important that one understand how it works. A lot of your jQuery code will use the jQuery class. You can use the jQuery class two different ways.
jQuery('#dom') – Full text way to use jQuery. You will only use this if the shorthand functionality is already being used by another library.
$('#dom') – Shorthand way to use jQuery. Does the same as above but is significantly shorter.
Very short and quick tutorial but this is one of the most important concepts that you understand in order to be successful with jQuery.