Content Delivery Networks (CDN) are a series of global servers installed with the intention of streamlining and optimizing content delivery to end users. This is accomplished by localizing the information being accessed in a region near the user to reduce the time it takes for that information to travel to and from the servers. There are plenty of moving parts to this system and AWS does provide its own set of tools for ensuring distribution of your content.
Amazon CloudFront is a content delivery network operated by Amazon Web Services. Content delivery networks provide a globally-distributed network of proxy servers that cache content, such as web videos or other bulky media, more locally to consumers, thus improving access speed for downloading the content.