Dynamic Names

One of Excel's most powerful features is the ability to define Names. A Name can refer to a single cell, a range, or a calculated value. You can even define a dynamic Name that refers to a changing range of cells.

You might need to refer to a list of items in your code, but you don't know how big the list will get or where someone might move it. To automatically sync the named range to the data, define a dynamic Name using the Insert -> Name -> Define menu, and this dialog:

The Refers To: field contains a couple of formulae instead of a cell reference, rephrased:
=OFFSET($B$2,1,0,COUNTA($B$2:$B$1000)-1,1)

The Offset formula defines a corner cell, how many rows away, columns away, how many rows to include, and columns to include.  

For the corner cell use the table header, not the first data item, because somebody might delete that cell. The CountA function in the How Many Rows parameter counts non-blank cells in the column.  The heading cell is included in the count, so subtract 1 from it's result to give the actual number of rows in the range.  This example sets an arbitrary limit of 998 items - your knowledge of the likely dataset and any use of the worksheet below the data table are factors in specifying this value.

Blank rows within the data would be a problem, so if that's a possibility, you can nest a few more functions to detect the range of cells you want... but it does get messy and there's no function help when editing names in the dialog, so be warned.

Anyway, now you can use that Named Range in code...

Dim rng as range
For Each rng in Range("Customer_List")
... some code
Next

And you're not putting any actual cell addresses in there so the code stays clean and safe.

An important factor when defining a Name this way is that your Reference formula needs to be safeguarded against possible edits to the worksheet. If a user deletes a cell which is part of the Name's RefersTo property, that Name could break, resolving to a #REF error for ever more. Good Excel programmers anticipate this possibility and set up Names (and Formula references) for maximum durability, helping workbooks live longer.