Returns a Workbook
object that represents the workbook in the active window (the window on top). Read-only. Returns Nothing if there are no windows open or if either the Info window or the Clipboard window is the active window.
expression.ActiveWorkbook
expression A variable that represents an Application object.
Example
This example displays the name of the active workbook.
Visual Basic for Applications
MsgBox "The name of the active workbook is " & ActiveWorkbook.Name