The Work Area is a time range defined by an In Point (start) and Out Point (end). It serves two purposes:
IOVisual indicator: The work area is shown as a light-colored highlight in the timeline ruler between the In and Out markers. Areas outside the work area are dimmed.
Shift and drag inside the work area band to slide the entire In-Out range without changing its duration.Ctrl+I for In, Ctrl+O for Out.In the export dialog, the "Export Range" selector offers: