CDN stands for Content Delivery (or Distribution) Network. It is a large system of the distributed servers over the Internet across multiple locations. The objective is to provide high performance and high availability of content to the end users.
In case of a downloaded local copy of Bootstrap, we add this in the HTML HEAD section:
<link rel="stylesheet" href="bootstrap.min.css"> <link rel="stylesheet" href="bootstrap-theme.min.css"> <script src="bootstrap.min.js"></script> ...