In Excel 2007 Microsoft introduced a new file format, Office Open XML which allows other programs to easily work with Excel workbooks.
Listed below is a list of the most common file formats you will use.
A standard Excel workbook that does not contain macros. This is the format for most basic format for versions of Excel 2007 and above.
An Excel workbook file that contains macros. This is simply a workbook that has program code (Macro/VBA) embedded within it.
An Excel workbook template that does not contain macros.
An Excel workbook template that contains macros.
An Excel add-in file.
A binary file similar to the old XLS format but able to accommodate the new features.
A backup file
Excel 97-2003 Workbook
This is the old format that allows users with earlier versions of Excel to read your workbooks. Some features won’t work in earlier versions and if you’ve used those in your workbook Excel will display a warning when you save telling you which features will be lost.
The bottom part of the Compatibility Checker lists the potential compatibility problems. To display the results in a more readable format click the Copy to New Sheet button. Keep in mind that compatibility problems also can occur with Excel 2007 and Excel 2010 even though these versions use the same file format as Excel 2013. You can’t expect features that are new to Excel 2013 to work in earlier versions. For example, if you add Slicers to a table (a new feature in Excel 2013) and send it to a colleague who uses Excel 2010 the Slicers won’t be displayed. In addition formulas that use any of the new worksheet functions will return an error. The Compatibility Checker identifies these types of problems.
If you need to send a worksheet to a user who does not own a copy of Excel you can save it in PDF (Portable Document Format). This format was invented by Adobe and is also sometimes called Adobe Acrobat or simply Acrobat. Adobe provides a free reader program for PDF files and most users will already have this installed upon their computers. If you send a user a PDF file they will be able to read and print the PDF document but not be able to change any of the data.
Open a blank workbook.
Press F12 on your keyboard
Click the Save As Type dropdown menu.
Select which file type is best for your workbook.
Name your workbook and click Save.
CHANGE THE DEFAULT FILE FORMAT
The default file format in Excel 2007 and beyond is .xlsx.
If for example you use macros frequently you may want the default format to be .xlsm.
Click the File tab.
This will open the Excel Options dialog box.
Select the Save tab in the dialogue box.
You will see an option Save files in this format and a dropdown box.
Select your preferred file type from the options.
Once your option is selected click OK in the dialogue box.
Your default file format has now been changed.