### This is Tutorial How to Convert XLSX to XLS converter is not Application ###
How to Convert XLSX to XLS - Convert XLS Files to XLSX Files
Microsoft Excel is a spreadsheet application that is part of the Microsoft Office product suite. The extension .xls denotes that the file is a Microsoft Excel file. With the launch of Office 2007, Microsoft changed the default file extension to .xlsx. This new file format is part of Microsoft's Open XML format, which results in a smaller file size and better data integration with external sources. If you have a file with the extension .xls, you can easily convert it to the newer .xlsx file format.