XLS files are Excel files that use the Binary Interchange File Format (BIFF). This was the default format for Excel versions 97-2003.
XLS files can have multiple sheets, and each sheet can contain multiple rows and columns of data. They support various data types, including text, numbers, dates, and formulas.
Key features of XLS files include:
- Works with older versions of Excel and other spreadsheet software
- Can store formatting information, charts, and macros
- Smaller file size compared to newer formats like XLSX
- Limited to 65,536 rows and 256 columns per sheet
While XLS files are still widely used, they're gradually being replaced by the more modern XLSX format.