Renaming sheets
By default, the name for each new sheet added is SheetX, where X is the number of the next sheet to be added. While this works for a small spreadsheet with only a few sheets, it can become difficult to identify sheets when a spreadsheet contains many sheets..
You can rename a sheet using one of the following methods:
Enter the name in the Name text box when you create the sheet using the Insert Sheet dialog (Figure 14 on Page 23).
Right-click on a sheet tab and select Rename Sheet from the context menu to replace the existing name with a different one.
Double-click on a sheet tab to open the Rename Sheet dialog.
Note
Sheet names must start with either a letter or a number; other characters including spaces are not allowed. Apart from the first character of the sheet name, permitted characters are letters, numbers, spaces, and the underscore character. Attempting to rename a sheet with an invalid name will produce an error message.