An operating system installed in myriad handheld devices, appliances, equipment and vehicles. The criterion that makes an OS an embedded OS is that it is installed into the firmware of the device rather than the hard disk. It is also generally not user-installed, although in the smartphone and tablet world, upgrades are downloaded and automatically installed at future intervals. Embedded operating systems are typically much more compact than their desktop counterparts and are often designed for real-time operations. See embedded system, embedded Linux, QNX, OS-9, Windows XP Embedded, Windows CE, VxWorks and Symbian.