How to Open an XLS File in Excel. 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 ...

If you cannot open an Excel file and see Excel cannot open the file because the file format or extension is not valid error, see this post.

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 ...

If you use Microsoft Excel on your Mac, you can save the spreadsheets you create and open them in Numbers, Apple’s spreadsheet app. It’s a handy feature to use in case you can’t access Microsoft’s ...