There are generally two scenarios where you will encounter a PST file:

Open and find items in an Outlook Data File (.pst) - Microsoft Support

Microsoft Outlook remains one of the most widely used email clients in the corporate and personal world. At the heart of its data storage architecture is the . Understanding where these files are located, how they work, and how to manage them is crucial for troubleshooting Outlook issues, migrating to a new computer, or freeing up hard drive space.

(Scan may take time; focus on Users folder.)