What is a personal store file (.pst)?

A personal store file (.pst) is a file used to store local copies of messages, calendar events, and other items like rules within Microsoft Outlook. PST stands for personal storage. 

You can see your pst files under File/Data File Management. In Outlook (97-2002), the storage limit for a single user's .PST file is 2 GB. Begining with Outlook 2003, the limit is 20 GB. 

You should not try to modify a .pst file, nor move it to a new location. Doing so could cause errors and require you to recreate the Outlook Group.

Please also note the following FAQ articles: