Compatibility Mode

Microsoft introduced a new file format in Office 2007. Office documents created with older versions of Office utilized an older file format. See the table below for file extensions for the old and new formats.

Office Application	Old File Extension	New File Extension
Word	.doc	.docx
Excel	.xls	.xlsx
PowerPoint	.ppt	.pptx

 

You can continue to work with both older and newer formats in Office 365. However, when accessing older file formats using Sharepoint on the web, you will not be able to edit the files without upgrading to the new file format. For example, if you open a Word document that has a .doc extension from Sharepoint online, the file opens in the web browser as read only. If you wish to edit the document in the web browser, you will be prompted to convert the file:

Converting the file will result in the creation of a new file. The old file is retained with the .doc extension and a new file is created with the same name but a .docx extension.

If you wish to edit the file without converting, choose Open in Desktop App.

Note that converting files may affect the format/layout of the document and may require some adjustment after conversion. Also, to avoid duplicate files, delete the old file after conversion.