Essentially, it gets rid of the contents and formats of all cells highlighted. In earlier versions of Excel, it selected Edit | Cle ar | All. This last step is an old shortcut that still works to this day. Often you don't know why it's happened, and you can't find any data anywhere near those extremes. It's basically saying that there's something at the far right of your worksheet (column IV pre–Excel 2003 column XFD thereafter), or else at the very bottom (row 65,536 pre–Excel 2003 row 1,048,576 thereafter). I adore its use of the 'off of' artificial construct. Select another location in which to insert new cells, or delete data from the end of your worksheet.
To prevent possible loss of data, Excel cannot shift nonblank cells off of the worksheet. When you try, it will give you the following error: Sometimes you'll encounter a spreadsheet that doesn't allow you to insert a new column.
