Hang
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- This page is about the computer malfunction called hanging. For other meanings, see hang (disambiguation). For the capital punishment, see hanging.
In computing, either a single computer program or the whole system may "hang" or become unresponsive to keyboard and mouse input. The term "hang" is synonymous with "freeze," the more commonly used term. In a hang, the window affected or the whole computer screen becomes static, the latter case including the mouse cursor. Contrast with crash, where a program exits abnormally with an error message. When no other input works, the power cycle must be restarted by an on/off or reset button.
The cause of a hang is usually that the programmer has incorrect termination conditions for a loop, or, in a co-operative multitasking operating system, forgetting to yield to other tasks.
Unstable electricity is an underestimated cause for hangs. More hangs than most people realize are due to interferences in the electricity [citation needed].
Usually, in systems with a modern operating system, the user is able to terminate the programs running (for instance, with the kill command, or through the "end task" button on the task list in recent versions of Microsoft Windows), and, if they wish, restart it in the hope that the anomalous condition that caused the hang does not recur. Older systems, such as those using MS-DOS or Microsoft Windows 3.1, often needed to be completely restarted in the event of a hang.
Most newer systems, such as Windows 2000/XP, Apple Computer's Mac OS X and Linux crash less often; they do not need to be totally restarted in the event of a hang.
A watchdog timer can reboot the computer in events of a hang.
