JQuery is a collection of JavaScript. jQuery simplifies the programming of JavaScript also it is easy to learn.Because of its less write and more work.It simplifies the HTML and DOM manipulation.It is free open software more advantage to the developers. JQuery library contains following libraries HTML/DOM manipulation CSS manipulation HTML event methods Effects and animations AJAX Utilities Major thing in JQuery is ,that is it run mostly same in major web browsers.Biggest advantage of this is ,because of its wide usage and user already download the file therefore when it is loaded it will loaded from cache. We can access the jquery with online link or from our file. < head > < script src ="jquery-3.3.1.min.js" > < /script > < /head > online < head > < script src ="https://ajax.aspnetcdn.com/ajax/jQuery/jquery-3.3.1.min.js" > < /script > < /head >