XLSX is the current standard file format for Excel, but it was XLS until Office 2007. The main difference is that XLSX is an XML(extensible markup language)-based open file format, and XLS is a proprietary Microsoft format. XLSM is an XLSX file that is macro-enabled. Macro-enabled means that it can store instructions to record repeated steps in a spreadsheet program. The macros are programmed in Microsoft Visual Basic for Application (VBA) from the Excel Workbook. The Visual Basic editor is used to record and run macros in Excel.