Scaffold implements the basic structure of a Material Design or iOS Cupertino visual layout. For Material Design, the Scaffold widget can contain multiple Material Design components:

• body: The primary content of the scaffold. Its displayed below AppBar, if any.
• AppBar: An app bar consists of a toolbar and potentially other widgets.
• TabBar: A Material Design widget that displays a horizontal row of tabs. This is generally used as part of AppBar.
• TabBarView: A page view that displays the widget that corresponds to the currently selected tab. Typically used in conjunction with TabBar and used as a body widget.
• BottomNavigationBar: Bottom navigation bars make it easy to explore and switch between top-level views in a single tap.
• Drawer: A Material Design panel that slides in horizontally from the edge of a scaffold to show navigation links in an application.

In iOS Cupertino, the structure is different with some specific transitions and behaviors. The available iOS Cupertino classes are CupertinoPageScaffold and CupertinoTabScaffold, which are composed typically with the following:

• CupertinoNavigationBar: A top navigation bar. It's typically used with CupertinoPageScaffold.
• CupertinoTabBar: A bottom tab bar that is typically used with CupertinoTabScaffold.