A Mautic instance migration is the process of copying Mautic resources between two instances, exporting resources from an instance or importing resources into one.
Migrations can be requested manually or can also happen automatically (in case of instance cloning for example).
When importing or copying, each resource is identified by a unique property depending on the type of resource. For example users use their e-mail addresses as identifiers, landing pages use their alias fields and so on.
This process ensures that no two resources of a type can be mistaken for each other, which is important in order to avoid creating duplicates.