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.

If you notice that your Excel files are opening in Notepad, then read this post to learn how to fix the issue. The default behavior of a document or file is to open in the application with which it ...