After you create the group, the word "group" appears in the title bar of the workbook. Once they are grouped you can format one worksheet and all of the worksheets will have the same formatting. You can insert a row in a worksheet and the same row will be inserted into all worksheets. This is a great tool when you need for all of your worksheets to have the same formatting.
How does Excel store Worksheets? Worksheets are saved in an Excel file called a workbook. These workbooks are what Excel uses to collectively organize all the different related parts of many different related worksheets as well as the related charts, graphs and various other objects within Excel.