OST vs. PST — What's the Difference?

OST and PST are both file extensions used by Microsoft's Outlook email client but serve different purposes. OST, or Outlook Offline Storage Table, enables users to work offline by creating a local copy of the mailbox that later syncs when online. PST, or Personal Storage Table, is often used for archiving and transferring Outlook data, and does not require synchronization with the server.

OST files are generally associated with an email account and automatically created by Outlook when you set up an Exchange, Outlook.com, or IMAP account. These files enable seamless working, even without an internet connection, as changes are synchronized when you reconnect. PST files, on the other hand, are typically created manually by the user and store copies of messages, calendar events, and other items from Outlook, providing a way to backup or move data.

OST files are more secure because they are bound to a specific computer and a specific user profile. You can't simply move an OST file to another computer and access its data. PST files are less restrictive; you can open a PST file from any computer with Outlook, making them more flexible for sharing and backing up data but less secure.

In summary, OST files are meant for offline access and seamless synchronization of your mailbox with the email server. They are generally not portable between different computers or user profiles. PST files serve more as a way to archive, backup, or transfer email data and can be moved from one computer to another. Both are integral to managing Outlook data but are utilized for different needs.