Microsoft Outlook stores all of a user's personal information (such as email messages, contacts, calendar events, tasks, and journal entries) in a single file that ends with a .pst extension. Often this file is named Outlook.pst.
all data is generally stored in a single file with a pst-extension
PST itself a file format of Microsoft Outlook email client. So, I think you are bit confuse about your query.PST file single file format which stores all the information of MS-Outlook such as emails, attachments, contacts, address and so on. Outlook uses the .pst extension to save their database.For more about Outlook PST Data File, go to the source link.
Its depend which mode you are using in Outlook. If MS-Outlook is connected to exchange server, then it will create an OST file (.ost extension) on the local system.On the other hand, if the Outook is working single (without any connectivity with server) having a connection with any web based email account or IMP/POP3, then PST File (.pst extension) is the file extension for Microsof Outlook 2007.
.pst
PST stands for Personal Folder File.
How to Increase Outlook PST File Size
An Outlook PST file exceeding the 50 GB size limit is prone to corruption and may result in a "cannot open the PST file" error. In case the PST file gets corrupted, you will not be able to access the PST file and its contents unless the file is repaired. Greetings, Peter
Yes, we can access Outlook PST file in Outlook 2011 but first you need to convert PST File into EML File.
Most probably the .pst file is damaged. Try running scanpst.exe (installed along with Outlook on your system) on the pst file. It repairs the file and makes it resuable. Outlook Pst file doesn't opens because of many reasons like corruption of PST file, PST size getting bigger than 2gb. Try to use recover pst file thanks to application below under all Windows OS, beginning with MS Windows 98
What is the file extension What is the file extension
Microsoft Outlook creates a PST file, while you configure an account in Outlook. The PST stores copies of messages, calendar, notes, tasks, contacts and other items. PST file may get corrupted because of many reasons, in that case, you would be unable to open Outlook. The reasons could be Virus, improper outlook shutdowns, corruption in header files, pst file has reached maximum size limit etc. In that case you can use outlook utility, named Inbox repair tool to fix your pst file.
Some of the important file extensions of Outlook and Outlook Express are mentioned as below :Microsoft Outlook :Outlook Data File (.pst)Offline Folder File (.ost)Personal Address Book (.pab)Offline Address Books (.oab)Messages (.msg, htm, .rtf)Stationary (.htm)Rules (.rwz)Outlook Express :Outlook Express data file (.dbx)Email Files (.eml)Email messages as text files (.txt)Address book (.wab)Contact information (.vcard)Internet Account files (.iaf)