CDN

A CDN (Content Delivery Network) is a mechanism used to spread content (videos, images, code etc.) across the globe, so it can more efficiently be downloaded.

When you download a file without a CDN, that file needs to be retrieved from storage and sent to your computer.

Now if you are in India, and the file is on a server in the US, the file has to travel all the way across the globe, to reach your computer.

A CDN creates a copy of the file on a server in India, so your it's much closer to your computer, and therefor can be downloaded much quicker, and doesn't need to connect all the way to the US.

This also has the extra added benefit of relieving pressure from the server in the US.

This mechanism of spreading content across the globe, is called a CDN.

It's a network of servers, used to deliver content more efficiently.

A CDN is not limited to only serving certain files, it can serve any static file at all.

If you have some javascript on your website that gets loaded every time someone opens your website, you can spread this on a CDN so they load the javascript from the nearest server, making your website faster, and your servers less busy.

These servers are also called POPS (Points Of Presence). They are points where your files are present.