jQuery has the $() function that actually selects a web page's parts. Any CSS selector expression or DOM node can be passed as argument; its results are all found elements.
So we can easily use them for manipulation in order to modify their behavior.
$('div') will access all div elements
$('#X') will access all elements with id X
$('.x') will access all elements which class is x
$('p') will access all paragraphs in a web page
Let's say that we want to add a class 'newclass' to all paragraph elements. We need to add the following lines after jQuery library is loaded: