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 button, some content would slide out. The jQuery code would look like this:$(document).ready(function(){
$('button').on('click',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.