The scroll bar component creates a scroll bar that you can use to scroll the contents of a window, form, or other control. In the OnScroll event handler, you write code that determines how the control behaves when the user moves the scroll bar. 

The scroll bar component is not used very often, because many visual components include scroll bars of their own and thus don't require additional coding. For example, TForm has VertScrollBar and HorzScrollBar properties that automatically configure scroll bars on the form. To create a scrollable region within a form, use TScrollBox.