download a jQuery file and store it within your project
Use a CDN (content delivery network)
<html>
<head>
<title>Add jQuery by downloading jQuery file(s)</title>
</head>
<body>
<script src="js/jquery-2.1.4.js"></script>
<script src="js/app.js"></script>
</body>
</html>
<html>
<head>
<title>Add jQuery using a CDN</title>
</head>
<body>
<script src="//code.jquery.com/jquery-2.1.4.js"></script>
<script src="js/app.js"></script>
</body>
</html>
A content delivery network (CDN) places files in different locations so that the person using your webpage can receive the nearest copy of it faster
Prevents your users’ browsers from downloading commonly used libraries(like jQuery) every time they visit your site
Use of CDNs increases page speed for highly trafficked sites
Click here for a nice overview of CDNs