Excel Macros and Workbook Events
Workbook events occur when something happens to a particular Excel workbook. For example, when a workbook is opened, when a workbook is closed, when a new worksheet is added, or when a workbook is saved. Each workbook is its own built-in module where you can place your own event procedure.
To get to this built-in module, you will need to first activate the Visual Basic Editor (press Alt+F11). Then in the Project Explorer menu, right-click on ThisWorkbook, and then choose the ViewCode option.
The Visual Basic Editor will automatically open to the built-in module for the workbook. This module will have two dropdown boxes at the top.
Select the Workbook option in the dropdown on the left. This action will automatically select the Open event in the dropdown on the right. As you can see here, this will also added some starter code where you can enter or paste your code.
The idea is to choose the most appropriate event from the Event dropdown for the task at hand. The following figure illustrates some of the events you can choose.
The more commonly used workbook events are as follows:
Worksheet_Open: Triggers when the workbook is opened
Worksheet_BeforeSave: Triggers before the workbook is saved
Worksheet_BeforeClose: Triggers before Excel closes the workbook
Worksheet_SheetChange: Triggers when a user switches between sheets