The change to these XML-based formats supports new features and helps make your documents:
Safer by separating files that contain scripts or macros, making it easier to identify and block unwanted code or macros. Smaller in file size. Less susceptible to damage or file corruption.
For most people using Microsoft Office 2019, the change in file format will likely be seen in the file extensions used for naming files. Conversion options are available on both sides but require patience and knowledge to build a successful strategy for exchanging Office files.
How Has Naming Changed?
In earlier versions of Microsoft Word, files were saved with the .doc extension, Microsoft Office Word 2019 files now use the .docx and .docm file extensions. Excel workbooks have exchanged their .xls file ending for new .xlsx or .xlsm extensions in Excel 2019. Presentations in PowerPoint have long been saved with a .ppt ending whereas, now, in Microsoft Office PowerPoint 2019, the extensions are either .pptx or .pptm. Why multiple options for file name extensions in Office 2019? The differences depend on whether or not a file contains macros or programming code. The letter "m" at the end designates possible macros or programming code in a file. Other less commonly used file extensions may also appear on Office 2019 files. Just a reminder: this dramatic change to file formats is much more than just a cosmetic switch in file naming conventions, and so, editing the extension will not convert a file from one type to another.
EASY TIP: How can you tell the difference between Office 2019 and Office 2013 files? View your files from Windows Explorer. The file is an Office 2019 file format if it has a 4 character extension; it is an Office 2013/2016 (or earlier) file format if it has a 3-character extension..source office.com/setup
Microsoft Office Access 2019 databases are also saved with a new file format, .accdb, or can be created with the same file format as earlier versions,.mdb, to allow for continued easy access to data. Once an Access database is converted for use with Access 2019, however, it is no longer available for use with earlier versions of Microsoft Access. Notice as well that Access 2019 databases are saved with a 5-character extension.
File Compatibility Between Versions of Microsoft Office
If you are one of the first in your group to get the Microsoft Office 2019 system, you can still share documents between Office 2019 and earlier version of Office. Important considerations when working in Microsoft Office 2019
With Office 2019, you can open a file created in Office 95 through Office 2013. When you save a file created in a previous version, the default in the Save As dialog box is to save the file as the same previous version. You can also choose to save the file as a 2019 version. A convert option in each key Office 2019 program gives you the choice to convert an older file to the new program file format. Each Microsoft Office 2019 program can be customized to change the default file format to save as an Office 2013 format. When you save a file as a previous version, a Compatibility Checker will let you know of any Office 2019 features that may be disabled, or matched as closely as possible. Colleagues who have Office 2010 through 2013 can work in your 2019 files using a converter that will let them open your document.
Find out how to download conversion tools at