Excel 2003:
.xls = Workbook
.xla = VBA Add-in
.xlb = Toolbar (where custom toolbar settings are stored)
.xlc = Chart
.xld = Dialog (from older versions of Excel)
.xlk = Archive (Excel spreadsheet backup)
.xll = DLL Add-in
.xlm = Macro
.xlt = Template
.xlv = VBA Module
.xlw = Workspace (collection of multiple Workbooks)
Excel 2007:
.xlsx = Workbook (XML format)
.xlsm = Macro-enabled Workbook
.xlsb = Excel Binary Workbook (instead of XML format)
.xltm = Macre-enabled Template
.xlam = Add-in (XML format)
http://wiki.answers.com/What_is_the_file_extension_that_indicates_an_excel_file#ixzz16E1eq6Mr
FormatExtensionDescriptionSpreadsheet.xlsMain spreadsheet format which holds data in worksheets, charts, and macrosAdd-in (VBA).xlaAdds custom functionality; written in VBAToolbar.xlbThe file extension where Microsoft Excel custom toolbar settings are stored.Chart.xlcA chart created with data from a Microsoft Excel spreadsheet that only saves the chart. To save the chart and spreadsheet save as .XLS. XLC is not supported in Excel 2007 or in any newer versions of Excel.Dialog.xldUsed in older versions of Excel.Archive.xlkA backup of an Excel SpreadsheetAdd-in (DLL).xllAdds custom functionality; written in C++/C, Visual Basic, Fortran, etc. and compiled in to a special dynamic-link libraryMacro.xlmA macro is created by the user or pre-installed with Excel.Template.xltA pre-formatted spreadsheet created by the user or by Microsoft Excel.Module.xlvA module is written in VBA (Visual Basic for Applications) for Microsoft ExcelLibrary.DLLCode written in VBA may access functions in a DLL, typically this is used to access the Windows APIWorkspace.xlwArrangement of the windows of multiple Workbooks
In older Word files (before 2007), it is common to see .doc
In newer Word file (2007 and later), it is common to see .docx
.xls is the normal file extension for a spreadsheet
.xlt for a template
There are 2 of them: ppt and pptx.
.htm
* The file extension of a Word document is .doc * The file extension of an Excel speadsheet is .xls
"Docx" is the default file extension for Word 2013 edition.
"Docx" is the default file extension for Word 2013 edition.
The default extension of a Telugu word file is usually .docx if it is a Microsoft Word document or .odt if it is an OpenDocument text file.
The most common file extension for a Microsoft Word document is .DOC. However, there are others.You can read more using the link, below.
.docx The extension docx is used in Word 2007.
A Microsoft Word file has a .doc extension.
For most typical Word documents the extension is .docFor Excel workbooks (spreadsheets) the extension is .xlsIn general the file extension is the 3 letter/number "code" after the period in the complete file name that gives a hint as to what type of file it is. For example, in the file name resume.docthe word resume is the file's actual name and the .doc tells you that it is a document file.
.docx
The extension. It tells Windows what kind of a file it is. For example, a file with the ".doc" extension is a Microsoft Word Document.
.doc just say hey I'm a old word processing file extension and this is how I need to be opened, so you can read me.