jQuery is a JavaScript library that allows interaction with the HTML and CSS. Every good site uses jQuery, espcially ones that use buttons and animation. Let’s say when you click this , some content would slide out. The jQuery code would look like this:$(document).ready(function(){
$(this).append('Some Text');

What happens is this: When the HTML code is ready, watch for the event of clicking the button. When that event happens, add some text. It is a lot quicker than using Angular or something else.