Editing Process (computing) (section)

===Process states===
{{Main|Process state}}
[[File:Process states.svg|right|300px|thumb|The various process states, displayed in a [[state diagram]], with arrows indicating possible transitions between states]]

An operating system [[kernel (operating system)|kernel]] that allows multitasking needs processes to have [[process states|certain states]]. Names for these states are not standardised, but they have similar functionality.<ref name="OSC Chap4"/>

* First, the process is "created" by being loaded from a [[Auxiliary memory|secondary storage]] device ([[hard disk drive]], [[CD-ROM]], etc.) into [[main memory]]. After that the [[Scheduling (computing)|process scheduler]] assigns it the "waiting" state.
* While the process is "waiting", it waits for the [[scheduling (computing)|scheduler]] to do a so-called [[context switch]]. The context switch loads the process into the processor and changes the state to "running" while the previously "running" process is stored in a "waiting" state.
* If a process in the "running" state needs to wait for a resource (wait for user input or file to open, for example), it is assigned the "blocked" state. The process state is changed back to "waiting" when the process no longer needs to wait (in a blocked state).
* Once the process finishes execution, or is terminated by the operating system, it is no longer needed. The process is removed instantly or is moved to the "terminated" state. When removed, it just waits to be removed from main memory.<ref name="OSC Chap4" /><ref name="Stallings">{{cite book |last=Stallings |first=William |date=2005 |title=Operating Systems: internals and design principles |edition=5th |publisher=Prentice Hall |isbn=0-13-127837-1}} (particularly chapter 3, section 3.2, "process states", including figure 3.9 "process state transition with suspend states")</ref>