It is a CDN service from AWS that allows you to distribute Static Content (S3) and Dynamic Content cached content in edge locations. It also provides you with Cloudfront Cache invalidation and object versioning.
It is commonly used for distributing frontend applications from S3 bucket.
CloudFront concepts
Time To Live (TTL)
Cloudfront Cache Behaviour
Price Class
CloudFront Restriction
Origin Access Control
Cloudfront Cache invalidation