SDI is the abbreviation for Single Document Interface. SDI means that each workbook opens in its own window and has its own interface. This provides a lot of useful functionalities.
Benefits of dual screen with SDI
When you work with two monitors in a dual screen setup, showing two workbooks in the same Excel instance was not easy to do. Now with SDI, you can have a workbook on each screen.

Move or Copy between worksbook
With the SDI, moving a worksheet from one workbook to another is very easy; it is like moving a file from a folder to another one.
To move one worksheet to another workbook
- Put your 2 workbooks side by side
- Drag and drop a worksheet from the first workbook to the other one.

If you want to copy your worksheet, press the Ctrl key while you drag and drop.
