Excel has a new file format. You can still open and edit older workbooks in Excel 2007, and share your files with people who don't have Excel 2007 yet.
Excel 2007 has a new file format. Why? Increased security for your files; reduced risk of file corruption; reduced file size; and new features.
Don't panic, you will not have problems opening and editing an older workbook in Excel 2007.
Read on to find out how you can share your Excel 2007 worksheets with people who don't have Excel 2007 yet, and to learn more about why the file format change was made.