What is the process of CloudFront?

Users query an edge location for a file. If the EL does not already have that file cached, it will connect to the origin to get it. That file is then streamed to the user. Once that happens once, that file is cached at the edge location for the TTL (time to live (default is 24 hours)) so that more users can get it without connecting to the origin. Object cache can be cleared, but user will be charged.