TPageControl is a component that provides a container to hold pages, much like a real-world notebook. TPageControl is a descendant of TWinControl and is available under the Common Controls tab of the Component Palette.
Unlike a TTabControl, each tab is connected to its own page. Pages (TTabSheets) from a TPageControl are accessible through its (non published) Pages property. Right-click on a TPageControl to show its context menu, and use 'Add Page' to create a new page.
The current (active) page is accessible through the ActivePage property.