An XLS file is a spreadsheet file created by Microsoft Excel, the most widely-used spreadsheet program. It stores data in a table with rows and columns and is often used to create charts and graphs. The table cells in the file may contain manually entered data or the results computed from the data of other cells.
NOTE: Excel 2007 and later saves spreadsheets in the OpenXML format with the .XLSX file extension.
Common XLS Filenames:
Workbook1.xls - The default filename Microsoft Excel gives to new spreadsheets prior to Excel 2007, which creates new spreadsheets with the Workbook1.xlsx filename.