All you need to do is add an external reference the resource in your HTML, e.g.:
This gives you multiple advantages, as:
- you don’t have to store files on your hosting
- you don’t have to worry about caching
- you can decrease the bandwidth usage of your server
- most likely you site’s overall performance will increase
- you’re able to write a “single html” page e.g. for testing reasons using heavy JS / CSS frameworks, and send a single file over e-mail & etc.
I like Microsoft’s explanation why CDN should be used:
Using a CDN can significantly improve a website’s end-user performance, since it enables browsers to more quickly retrieve and download content. For example, instead of having a browser request for an image traverse all the way across the Internet to your web server to download, a CDN can instead serve the request directly from a nearby “edge cache” server that might only be a single network hop away from your customer (making it return much faster – which makes your pages load quicker).