Too Long; Didn't Read
ENV files are plain text files that store variables and secrets that you would not want hardcoded in your codebase. These files live on your local machine which means you do not need a network connection to fetch your secrets. The open source community supports these files so there is a ton of support by the open-source community for parsers and managers. There isn't a standardized Schema that all libraries use. This is because each library is deciding the Schema of a ENV file instead of strictly following an open standard.