For storing documents as the basic Microsoft Excel format, right up to the Excel 2007 version, used its own binary format of files (BIFF) and the file extension was «.xls». In Excel 2007/2010, the basic format is the Microsoft Office Open XML format and stores document in files with the «.xlsx» extension. The Excel 2007 is compatible with binary formats such as CSV, DBF, SYLK, DIF, and others.