https://developer.apple.com/library/content/documentation/General/Conceptual/DevPedia-CocoaCore/Archiving.html#//apple_ref/doc/uid/TP40008195-CH1-SW1
Object archiving
Archiving is the process of converting a group of related objects to a form that can be stored or transferred between applications. The end result of archiving—an archive—is a stream of bytes that records the identity of objects, their encapsulated values, and their relationships with other objects. Unarchiving, the reverse process, takes an archive and reconstitutes an identical network of objects.
The main value of archiving is that it provides a generic way to make objects persistent. Instead of writing object data out in a special file format, applications frequently store their model objects in archives that they can write out as files. An application can also transfer a network of objects—commonly known as an object graph—to another application using archiving. Applications often do this for pasteboard operations such as copy and paste.
