Pst-files, unless you are using an Exchange or Outlook.com/Hotmail account, Outlook can’t live without them. The pst-file is also known as Personal Folders and Outlook Data File.
Knowing how to properly treat pst-files is one of the more important basic Outlook skills.
This guide contains these basics but also more advanced and additional background information about the pst-file and how you can handle them.
Continue reading: About the Outlook PST-File