To get a site feature from development to production, it goes through four servers:
- Quality Assurance (QA)
Except for the development server, which is localhost, there are times people, other than developers, need access to view a particular site on the QA or staging server. In addition, sometimes you need to test your site externally, whether it’d be a mobile device not connected to the network or an external, automated service. This means that the aforementioned servers need to be publicly accessible, but without being accessible to just anyone.