and only the root user can log in. It can do emergency repairs or maintenance, including resetting users' passwords on the machine without the need to know the old one. macOS In macOS holding the shift key after powering up activates Safe Boot that has background maintenance features (Besides the mode selection, it runs a file system repair, and in Mac OS 10.4, it disables all fonts other than those in /System/Library/Fonts, moves to the Trash all font caches normally stored in /Library/Caches/com.apple.ATS/(uid)/, where (uid) is a user ID number such as 501, and disables all startup items and any Login Items). Unlike in Windows where safe mode with networking is disabled by default and requires using a safe mode with networking enabled, in the macOS Safe Boot always includes networking. On the Classic Mac OS versions 6, 7, 8, and 9, a similar mode to the Unix root is achieved by holding down the shift key while booting, which starts the system without extensions. Android The way that safe mode in Android can be activated differs per vendor. Safe mode can be disabled by rebooting the device. Application software safe mode Application software sometimes offers a safe mode as well. In the PHP interpreter, prior to version 5.4, safe mode offers stricter security measures. The Glasgow Haskell Compiler from version 7.2 offers "Safe Haskell" mode, restricting usage of functions such as unsafePerformIO. Mozilla Firefox's safe mode allows the user to remove extensions which may be preventing the browser from loading. Internet Explorer can run in "No Add-Ons" mode and Protected Mode. Cydia's MobileSubstrate also has a safe mode that allows the user to uninstall tweaks and extensions that may crash the SpringBoard. See also BOOT.INI Bcdedit MSConfig References External links Mac OS X: Starting up in Safe Mode Booting