In order for programs and [[interrupt handler]]s to work without interference and share the same hardware memory and access to the I/O system, in a [[Computer multitasking|multitasking operating systemssystem]] running on a digital system with a single CPU/MCU it is required to have some sort of software and hardware facilities to keep track of an executing processes data (memory page addresses, registers etc.) and to save and recover them back to the state they were in before they were suspended. This is achieved by a context switching.<ref name=":0">{{Cite book |last=Bovet |first=Daniel P. |url=https://www.worldcat.org/oclc/64549743 |title=Understanding the Linux Kernel |date=2005 |publisher=O'Reilly |others=Marco Cesati |isbn=0-596-00565-2 |edition=3 |___location=Sevastopol, CA |oclc=64549743}}</ref>{{Rp|___location=3.3}}<ref>{{Cite web |date=2021-06-10 |title=Difference between Swapping and Context Switching |url=https://www.geeksforgeeks.org/difference-between-swapping-and-context-switching/ |access-date=2022-08-10 |website=GeeksforGeeks |language=en-us}}</ref> The running programs are often assigned a [[Process-context identifier|Process Context IDentifiers]] (PCID).
In Linux-based operating systems, a set of data stored in [[Processor register|registers]] is usually saved into a process descriptor in memory to implement switching of context.<ref name=":0" /> PCIDs are also used.
