Wikipedia
Where a device needs a username and/or password to log in, a default password is usually provided that allows the device to be accessed during its initial setup, or after resetting to factory defaults.
Manufacturers of such equipment typically use a simple password, such as admin or password on all equipment they ship, in the expectation that users will change the password during configuration. The default username and password is usually found in the instruction manual …
Default password - Wikipedia, the free encyclopedia