A DB file is a database file used on mobile devices such as Android, iOS, and Windows Phone 7 mobile phones. It is often used to store contacts and SMS information but may store any type of device or application data. DB files are commonly stored in an SQLite database format but may also be locked or encrypted so the user cannot see the data directly.

DB files on mobile phones generally are not meant to be opened or edited manually, since they are support files that include information for the device or for an application. One example of a DB file is sms.db, an iOS support file that stores the user's text messages (located in the /private/var/mobile/Library/SMS/ directory on the device). Another example of a DB file is consolidated.db, a database file on iOS devices that automatically tracks location information.

Data file created by QQ, a Chinese online chatting program; may store the contact list or log of online chat sessions for a user account; used for storing application data locally and loading it through the program interface.

QQ DB files are typically saved to the \Program Files\Tencent\QQ\[Account number]\ directory.

Chat history file created and used by Skype, an application that allows you to make phone calls, messages, and video chats; contains your conversation history, which includes all the instant messages and call details that a user has sent to and received from contacts.

NOTE: You can transfer your Skype chat history to another device by replacing the main.db file on the new device with the main.db file that contains the chat history you want to keep.

Cache of thumbnail images that represent larger images in a Windows folder; stores small versions of images stored in a folder for quicker browsing; typically not seen unless the "Show invisible files" option is checked within the Windows view options.

Windows Thumbnail Cache files are named Thumbs.db by default. For more information about Windows Thumbs.db files, including how to prevent them from being created, follow these instructions.

Database containing objects and other information used in games developed with the X-Ray Engine; used by S.T.A.L.K.E.R.: Clear Sky, S.T.A.L.K.E.R.: Shadow of Chernobyl, and other GSC Game World games; similar to .GCF files used by Valve-based games.

NOTE: X-Ray Engine Database files may also use the extensions ".db0," ".db1," ".db2," ".dba," ".dbb," ".dbc," etc.