Activate / Select

Understanding the difference between Selecting and Activating

There is very little difference between activating a worksheet and selecting a worksheet.
The following means that worksheets "Sheet 1", "Sheet 2" and "Sheet 3" are all selected

Sheets(Array("Sheet1", "Sheet2", "Sheet3")).Select 

When more than one worksheet is selected the first worksheet is always the active worksheet.

Activating sheets is a slow process.
You can only ever activate a single worksheet.

Sheets("Sheet2").Activate 

Cannot activate different worksheets when several are selected

The first line will select three worksheets and by default the first worksheet will be the active worksheet.

Sheets(Array("Sheet1", "Sheet2", "Sheet3")).Select 

The second line will not keep the current selection but will infact just select the "Sheet2" worksheet.

Sheets("Sheet2").Activate 

This is different functionality to the Select and Activate when using a Range object.

ActiveSheet.Previous.Select ?? 

Selecting Sheets

Redim Preserve arNames(1 to 5) 
Sheets(arNames).Select 
Worksheets(2) 

Worksheet Name - This is different to the worksheet code module name
SS - emm.com/excel-vba-worksheet

You can use the worksheet code module name in your code which can be useful if you think the user might rename the worksheet.