A content delivery network is a series of edge servers (caching servers) which are located amongst several points of presence (PoP) across the world. All of our managed content is pushed throughout several CDN providers meaning that regardless of where visitors may be located, they'll still experience fast speeds when accessing your site.
A cache server stores your static site files for a defined period time and serves them directly to a client when they need access to them. The client's web browser will usually then cache the information, meaning that they won't have to make several requests for the same data from our servers. This means less server load for us, and less waiting times for them.