Publishing is almost always a workgroup activity, involving writers, editors, copy editors, layout artists , and production editors. Even when a person has multiple roles, most publications still involve multiple people. And that means that files go back and forth as edits are made, layouts are created, and text and other elements are adjusted to fit the available space. Like rival QuarkXPress, InDesign has a companion product called InCopy to facilitate this back and forth. InCopy is not as powerful as InDesign ‚ it's not a layout tool ‚ but it does let copy editors, editors, and other wordsmiths work on InDesign layouts to make sure headlines fit, stories fit, and captions can be written in context without needing a full copy of InDesign.
InCopy works best in a networked environment, where everyone shares files from a common folder. That way, a copy editor can work on a layout without worrying that the designer might be working on a local copy at the same time, for example.
InCopy is both a separate program that runs by itself for text editing of stories in an InDesign layout, and a plug-in that works with InDesign to provide shared-editing capabilities.