What is Cloudfront?

Amazon CloudFront is a web service famous for its speed in the distribution of static and dynamic .html, .css, .js, and image files. CloudFront delivers content with the help of edge locations – a global network of data centers. When users request content from Cloudfront there are almost no delays and the performance is impressive. For example,

• Content that is stored in the edge location is being delivered by CloudFront immediately
• Content that does not exist within the edge location is being retrieved by CloudFront. It may be done from an Amazon S3 bucket, a MediaPackage channel, or an HTTP server – the place where the source exists. 

To deliver content to users, Cloudfront carries out the following steps:

1. The end-user accesses your website or application and requests files.
2. Request to the edge location is being routed by DNS. Usually, DNS finds the nearest edge location to deliver content immediately.
3. CloudFront checks requested files cached in the edge location. If they exist there, it returns these files to the user.
4. If there are no files cached in the edge location:

a) CloudFront sends the request for image files to the Amazon S3 bucket or for HTML files to the HTTP server.

b) If the files exist in the Amazon S3 bucket and the HTTP server, then they are returned to the edge location.

c) CloudFront obtains the files and forwards them to the user.

d) These files are then being cached in the edge location by the CloudFront.