Device locks are temporary actions taken to prevent access to the system when users depart from the immediate vicinity of the system but do not want to log out due to the temporary nature of their absences. Device locks can be implemented at the operating system level or application level. User-initiated device locking is behavior- or policy-based and requires users to take physical action to initiate the device lock. Device locks are not an acceptable substitute for logging out of the system (e.g., when organizations require users to log out at the end of workdays). Publicly viewable images can include static or dynamic images, such as patterns used with screen savers, solid colors, photographic images, a clock, a battery life indicator, or a blank screen with the caveat that controlled unclassified information is not displayed.