Those kinds of fonts are called serif fonts.
That is not a function of Excel.
Similar question has been answered here:What_is_the_file_extension_for_Microsoft_excel_file
Typical Office 2007 documents use 4 letter extensions. These include .xlsx for Excel, .pptx for Powerpoint and .docx for Word. Access however, uses .accdb as an extension, so it has 5 letters.
File extensions for web pages usually are .html.
Excel :P
The xlsx file extensions are from Excel 2007 whereas xls is used in the earlier versions of Excel.Thanks
There is no reason why you cannot type that in. As there are letters in it, it will be treated by Excel as text.
You may be referring to column headings, which are always letters. They identify the columns.
Webpages usually end in one if these extensions: .php .html .htm .aspx
Worksheets do not have extensions. They are contained in files known as workbooks. A 2007 workbook extension is .xlsx.
I presume you mean 3 letter extension. In that case it is "xls". There are also other Excel extensions like "xlt", "xlw" and "xla", amongst others.
XFD