A Content Delivery Network (or CDN) is a network of servers positioned in various locations around the world that essentially host a mirrored copy of your website. Instead of the traditional method of hosting your website in one location (wherever your hosting company's data center is located), a CDN acts as if your website were hosted in multiple locations, without having to go through the trouble of syncing your website content between all the different hosts manually.
The first benefit in utilising a CDN is speed. Page loading times for your website are drastically reduced (as much as half), since each visitor receives the website data from whatever server is closest to their location. 1&1's US data centre is located in Kansas City, KS. If your website has a significant amount of traffic originating from the UK, website loading times may be significantly higher for those visitors, as the website must be transmitted from Kansas City, KS accross the ocean to the UK. Using the 1&1 CDN powered by CloudFlare, your website would be mirrored on a server in London (as well as 61 other locations) so that your UK visitors do not need to wait for the site to be transmitted from across the sea. Instead, it will be loaded from a server right within the country.
The second benefit in utilising a CDN is security. There are plenty of websites that receive seasonal traffic spikes (like Halloween stores, wedding photographers, landscaping services) or spikes in traffic due to advertising/marketing. Whether an anticipated spike in traffic or an increase in traffic due to a malicious attack, utilising a CDN helps protect your website. The CDN acts similar to a load balancer so that any large spikes in traffic will be rerouted to another server in the CDN that is not under such heavy traffic.
Taking advantage of the 1&1 CDN powered by CloudFlare means you will be able to take advantage of: