Storm,
From the Excel Help function found within Excel:
"To select all cells on a worksheet, do one of the following:
Click the Select All button...
etc.

It is quite simply called the "Select All button"

Regards

"Storm" wrote:

Hello there. I'm trying to identify a part in an Excel screen. It is the
small box that is to the left of the column header A and on top of the row
header 1. It is the box that when you click on, it will select the entire
content of the worksheet.

Does anyone know what this box is called?

Thank you.
Storm