Sometimes you need to loop through all the columns within a given worksheet, so you need to first ascertain what is the last column in the worksheet. So how can one do this reliably?

Well, if all you columns are visible, then you can use code such as:

Dim iLastCol        As Long
iLastCol = Sheets("YourSheetName").Cells(7, Sheets("YourSheetName").Columns.Count).End(xlToLeft).Column

Or

Dim iLastCol        As Long
iLastCol = ActiveSheet.Cells(7, ActiveSheet.Columns.Count).End(xlToLeft).Column

Now that is all fine and dandy, if all your columns are visible, but what happens when you need to identify the last column even if those column may or may not be visible? Once again, no major problem. We just need to tweak our code to something like:

Dim iLastCol        As Long
iLastCol = Sheets("YourSheetName").UsedRange.Columns(Sheets("YourSheetName").UsedRange.Columns.Count).Column

Or

Dim iLastCol        As Long
iLastCol = ActiveSheet.UsedRange.Columns(ActiveSheet.UsedRange.Columns.Count).Column

Now both can be very useful in different situations. Just beware that there is a difference depending on whether or not you want to include hidden columns in your count/loop.