Where does Outlook hide its main data files? The .PST or .OST files which have your email, calendar, contacts and more.
Outlook data files can be anywhere on your computer, but the default location is usually in a hidden folder:
\Users\<username>\AppData\Local\Microsoft\Outlook
\Users\<username>\Roaming\Local\Microsoft\Outlook
The location can vary a lot, depending on the Outlook version, Windows version, how you upgraded Office and, it seems, the relative positions of the sun and moon!
Go to Info | Account Settings | Account Settings | Data Files to see the exact path.
Open File Location will open that folder in Explorer.
Outlook data file types
.PST Outlook data files. These are used by all Outlook accounts except Exchange Server mailboxes.
.OST Outlook data files. For Exchange Server accounts including Office 365 hosting and Outlook.com
