# Understanding User and Kernel Mode

**URL:** <https://discourse.codinghorror.com/t/understanding-user-and-kernel-mode/405>\
**Category:** blog\
**Created:** [January 3, 2008, 12:00am UTC](https://discourse.codinghorror.com/t/understanding-user-and-kernel-mode/405 "2008-01-03T00:00:00Z")\
**Posts on this page:** 1\
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**Author:** ![Fox\_Cutter](https://discourse-cdn.codinghorror.com/letter_avatar_proxy/v2/letter/f/c4cdca/32.png) [@Fox\_Cutter](https://discourse.codinghorror.com/u/Fox_Cutter)\
**Post date:** [January 4, 2008, 12:00am UTC](https://discourse.codinghorror.com/t/understanding-user-and-kernel-mode/405/45 "2008-01-04T00:00:00Z")

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Another notable case where code went from User to Kernal was with NT 4.0. The GDI Code went from being just another process to living in Kernal space. There was a long history behind why it was a process (partly related to how the OS could have different personas) but it was slow.

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