.xls for all versions up to Office 2003, and .xlsx for all versions from Office 2007.
A document that is created by Microsoft Excel. Excel is a spreadsheet maker.
.xls
To indicate that the basic file format is XML in Excel 2007 and later.
Export the MS Works database file in a comma-delimited format, save the file, then import the file into MS Excel.
.xlsx is the file format used in Microsoft Office Excel 2007. It is NOT backwards compatible (i.e. Excel 2003 and earlier versions cannot open it). The file is XML based and smaller in size than the .xls format. It is possible to open, edit, and save a .xls file in Excel 2007 for backward compatibility.
Well, I would recommend converting PDF format files to excel format files with a PDF format file to excel format file converter. There are many PDF format file to excel format file converters offered for use.
It is a spreadsheet file format, and refers to the Microsoft Excel spreadsheet.For more information, see Related links below.
Microsoft Excel
.xlsx is the file format used in Microsoft Office Excel 2007. It is NOT backwards compatible (i.e. Excel 2003 and earlier versions cannot open it). The file is XML based and smaller in size than the .xls format. It is possible to open, edit, and save a .xls file in Excel 2007 for backward compatibility.
Default file format for Excel 2003: .xls Default file format for Excel 2007: .xlsx Note: You can't open lower version file format in upper version. If you want to do this then you will have to download the compatibility pack.
While Microsoft Office is not available on Unix-like systems, you can use other offices suites to open the Excel file format. Consider trying LibreOffice or OpenOffice.org; both are excellent open-source office suites that support most Microsoft Office file formats.
The default file name for all versions of Microsoft Excel is called "book1"