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.

Businesses that switch to Mac computers may encounter problems when attempting to open some file types, such as Excel Spreadsheet (XLS) files. Macs do not have a native program for opening XLS files, ...

This month's monster security patch for Office breaks Excel when it tries to open HTML files, and it seems unlikely Microsoft will fix the problem Excel users are reporting an odd bug in the way Excel ...