When I began work at Community Medical Centers, the first skill I learned well was working with Data Courier.
If you have worked with PeopleSoft or some other enterprise level software, you may have performed “migrations”. For PeopleSoft, a developer might produce a “project” to be migrated from a development environment to a test environment for testing and then into production.
For Epic, Data Courier is akin to a PeopleSoft “migration”.
A website called Health IT Social has a nice layout of typical Epic environments. In this case, they address a special case you will likely run into if you have upgraded your POC environment, for instance and need to migrate data to your TST and PRD environment which have not yet been updated. We went through this experience a number of times, and for awhile even had separate TST environments for ICD 9 and ICD 10.