Every software you use stores files on your drive with a specific extension.
Microsoft Outlook is one of the tools that save files with.pstand .ost.
What is the OST file?

Should you back up OST file?
How to back up OST file?
Continue to read the following content.

If your Internet connection is slow or unstable, this Outlook feature allows you to use it effectively.
Why need to back up OST file?
It allows you toautomatically back up dataandonly back up changed files.
Here is how to use it:
1.
Download and install MiniTool ShadowMaker.
Launch it to enter its main interface.
MiniTool ShadowMaker TrialClick to Download100%Clean & Safe
2.
Go to theBackuptab and click theSOURCEpart to chooseFolders and Files.
Click theComputertab and go toC:\Users\user\AppData\Local\Microsoft\Outlook.
Then, check the OST file and clickOK.
Click theDESTINATIONpart to choose a destination to store the file.
Its recommended to choose the external hard drive.
ClickBack Up Nowto start the process.
Therefore, you gotta ensure that your account is signed in.
Here is how to do that:
1.
Go toFile>Open & Export.
ClickExport to a fileand clickNext.
ClickComma Separated Valuesand clickNext.
Save the file to your desired location.
This method can be a bit complicated for someone who hasnt done it before, but its not impossible.
So, heres how you could do it:
1.
Go toFile>Tools>Clean Up Old Items….
2.
Click Browse… to grab the desired files and folders you wish to archive.
Final Words
Thats the information on how to back up OST file.
Just follow the methods here to do that.
Hope they can help you.