Excel Spreadsheets File Formats
xlsx
Allows you to open Excel workbooks in an earlier version of Excel.
Allows you to share your files or print your files using commercial printers. Can easily add to a website so you can open it and not edit it.
xlsm
An Excel Macro-Enabled Workbook file
html
Hypertext Markup Language - When you copy text from another program, Excel pastes the text in this format.
csv
Saves as a comma-delimited text file. Ensures that tab characters, line breaks, and other characters are interpreted correctly. Workbook only saves the active sheet.
txt
Saves as a tab-delimited text file. Ensures that tab characters, line breaks, and other characters are interpreted correctly. Workbook only saves the active sheet.
xml
Spreadsheet file format (2003)
xlt
Spreadsheet template formats