hey
Microsoft Excel (full name Microsoft Office Excel) is a spreadsheet application written and distributed by Microsoft for Microsoft Windows and Mac OS X. It features calculation, graphing tools, pivot tables and a macro programming language called VBA (Visual Basic for Applications). It is overwhelmingly the dominant spreadsheet application available for these platforms and has been so since version 5 in 1993, and is bundled as part of Microsoft Office. Excel is one of the most popular microcomputer applications to date.
check out these sites 4 more info.
^ http://support.microsoft.com/kb/840817/
^ http://msdn2.microsoft.com/en-us/library/aa140066(office.10).aspx
^ http://www-unix.oit.umass.edu/~evagold/excel.html
^ http://www.cof.orst.edu/net/software/excel/no-stats.php
^ http://www.practicalstats.com/Pages/excelstats.html
^ http://www.mis.coventry.ac.uk/~nhunt/pottel.pdf
^ http://support.microsoft.com/kb/214058/EN-US/
^ http://support.microsoft.com/kb/214326/en-us
^ http://www.joelonsoftware.com/items/2006/06/16.html