If you create spreadsheets in Microsoft Excel that you need to distribute to colleagues or coworkers who don't use the software, you'll need a way to transform your XLS or XLSX files into standalone ...
XLS files are Excel workbook files created in Excel 97 or Excel 2003. The 2007, 2010 and 2013 versions of the program use the XLSX format by default to save workbooks, but can also use the XLS format.