What is a CDN?
CDN stands for Content Delivery Network or Content Distribution Network, is a network system server located in different parts of the world that serves to distribute content within an application / web so that data / content submitted accepted more quickly. Each server has the exact same files to another server, so that virtually every server is a mirror of the other server.
By using a CDN: even though the server is located in Singapore, when there are visitors from Europe, it is not a Singapore server (where your website) that perform the response, but the CDN server that is located in Europe. Likewise, when there are visitors who come from USA, USA CDN server who did reponse to these visitors. Automatically CDN server will respond with a server that is closest to the visitor.
Function CDN (Content Delivery Network) in this case is to minimize the download time required by the client, for its own CDN is a network of servers located in different parts of the world, therefore the server that is closest to the client will be given priority to send the requested file.