Microsoft Excel Spreadsheet - Legacy (.xls)
The XLS file extension, short for "Excel Spreadsheet", is a legacy format used by Microsoft Excel for storing spreadsheet data. Introduced with Excel 2.0 in 1987, it was the primary format until the introduction of XLSX in 2007. XLS files contain data organized in rows and columns, supporting formulas, macros, and various formatting options, making them essential for data analysis and financial reporting. Despite being replaced by the more robust and secure XLSX format, XLS files remain widely used in many legacy systems and applications.