A content delivery network or content distribution network (CDN) is a large distributed system of servers deployed in multiple data centers across the globe. Their real value comes when you think about latency–the time it takes for your information to be delivered hundreds or thousands of miles away from your actual web server.
The video demo above does a pretty good job of explaining what that actually means.
You can buy and manually use your own CDN (we like MaxCDN) or use a web host that comes pre-integrated with one, like jHost, or look into one of JDM’s Loading Speed add-ons where we’ll do all the work for you (plus some).
There are also several WordPress plugins that include a super-easy, pre-built API for buying and leaveraging a CDN, like W3 Total Cache.