What is PST File?

Overview – What is PST File Extension?

PST stands for the Personal storage table is the default self-contained, stand alone, the structured binary file format used by the Microsoft Outlook. Personal storage table (pst) file is designed in order to keep the entire data at one place. This data includes emails, calenders, notes, contacts, tasks etc.

It uses fixed block based methodology for allocating memory. The file is enlarged by pre-defined sum of bytes and files preserves or save the information internally regarding the allocated and non-allocated blocks. So when email messages are added to PST file, the PST file size is adjusted accordingly by the Outlook application. When any messages are removed or deleted, file size remains unchanged marking space unallocated where future items will be saved. Thus it has become easier to recover deleted data from PST files.

The PST file created automatically when user creates Outlook profile on desktop either using the POP3 or IMAP configuration. The data in the PST file stored in compressed or encrypted form depends on the settings that you have made in Outlook Application.


ANSI » it is bequest format that has 2gb storage space limitation. It work only on the below versions of outlook 2002

UNICODE » The storage capacity of this pst file is 20 GB in outlook 2007 and up-to 50 GB in outlook 2010 and 2013. it also known as the advance format of pst file extension.

The PST file architecture is designed or structured in three layers:-

NDB » NODE DATABASE LAYER :-It includes the header information, file allocation information and the nodes and blocks that holds the message data and nodes that helps locate data. It has two nodes

  • node b tree
  • block b tree
node b treeblock b tree

LTP » (LIST, TABLE, PROPERTIES) :-It basically concerned with properties that its stores in two dimensional table.

MESSAGING LAYER :-It combines the above two layers into messages, attachments, properties and folders.

Category of Application

  • As the PST files stores the emails data. Therefore it is considered as Database files

Application Software

PST file only supported by the Microsoft Outlook desktop base email client.


Application /vnd.ms-outlook

File Signature:-

It has the following file signature:- hexadecimal 21 42 44 4e


Microsoft Outlook is the Pesonal information Manager developed by the Microsoft Inc. To store the Outlook data such as emails, calendars, tasks, journal etc,. Microsoft Developed the PST file Format.

Location of PST files

Microsoft Outlook 2016

Microsoft Outlook 2013

Microsoft Outlook 2010

Microsoft Outlook 2007

Microsoft Outlook 2003

PST File Creation in Outlook

Follow these Steps to Create New PST in Outlook

  • In the Home Tab, Click on New Items and then go to more items option. In more items select Outlook Data File
  • After then New dialog box open ups and the select the Outlook data file(.pst) and then click on ok to proceed
  • Type the name which you want to give the newly created Outlook data file(.pst)

How to Merge PST Files in Outlook?

There are two steps involved in the merging of pst file manually.
1. New PST File Creation
2. Import the data from the PST file to the newly created pst file.

For PST File creation, you can read the complete steps in the above section.

The Complete Steps to Import PST file in the newly created PST file.

  • Go to File tab located at Navigation bar then Click on Open & Export Option
  • Under the Import & Export Wizard, choose Import from another program or file option
  • Click on Next to Proceed
  • Select Outlook Data File(.pst)
  • Click on Next.
  • Then Click on Browse to select the file to import
  • If you do not want to import duplicates items then you can Check the Do not import duplicates items
  • Click on Next to proceeds further
  • Now, Click on Select the folder to import from
  • Check on the Include Subfolder and import items into the same folder option
  • Click on Finish