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.

What happens when you want to edit a Microsoft Excel .xlsx file on a Mac, iPhone or iPad? While it’s not quite as easy as opening .docx files in Pages for Mac, it’s not an overly complicated ...

If your Excel files are opening in Notepad on Windows PC, here's how you can reset the settings to make .xls, .xlsx, etc files open in Excel.

Spreadsheet Is Slow to Open in Excel 2007. Spreadsheets that contain complicated formulas and a lot of data can take a while to load when you open them in Excel 2007, but that's not the only ...