Microsoft Excel is an extremely useful spread sheet program of long standing. It has been used for everything from the mundane to mathematical and is an excellent tool for storing and graphing data, recording grades and performing accounting functions. Its ability to process cell based formulas and to display data attractively makes it the kind of classic software that may never grow old. Excel files include charts, macros, data and graph objects. When saved as XLSB files they are binary files using BIFF12 format which is not the same as the standard Open XML format (XLSX). XLSB files are significantly larger than their compressed counterpart XLSX files. Even so they are more likely to be more efficient when accessed from Excel software. Please note that XLSB files may be accessed with Excel 2007 and higher versions. Older versions of Excel may be able to access XLSB - Excel Binary Spreadsheet files via Open XML.