This article gives the complete answer of the question "What is CDN". A CDN (Content Delivery Network) is a great way to speed up your website and provide high availability and performance. It is a system consisting of a no of servers distributed around the globe.
CloudFlare is a Content Delivery Network (CDN) which increases the loading speed time of your website and provides it with increase security against attacks. They have 79 Data Centers distributed globally, which store your website static contents like Images, Scripts & CSS. These Data Centers provide all the visitors your website content at high speed.