Projects are good for group collaboration with shared file content. Chat rooms are good for topic specific group conversations. Therefore, we support adding files to projects but not to chat rooms. Adding a file will upload the file to the given project for previewing, allow opening the file via the desktop app, notify project members of file updates, and provide local copies in the project folder upon any update. Alternatively, attaching a file will only upload the file to the given conversation for viewing and will not sync the file locally.