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→What does an Operating System do?
An operating system performs four main functions:
=== 1. Manage Management and separate resources Separation of Resources ===
Think of the specifications that were advertised when you bought your last computer (or smartphone):
All of these are system resources. The operating system manages these resources to ensure that they are used effectively, and to ensure that there are no conflicts over their use.
As requested by the user(s), or as triggered by other considitions factors such as the time of day or operational requirements, the OS will create processes -- running copies of computer programs. Each process is allocated compute resources by being permitted to run on one or more computer cores. To run a large number of processes, the OS will switch between them, stopping one process and starting another as needed to ensure that all of the processes get a fair share of system resources (which may not always be an equal share).
The operating system will allocate the available memory to processes and to the operating system's internal operations. The OS will program the system hardware to ensure that no process can overwrite memory allocated to another process.
Display space is similarly shared; the operating system will ensure that multiple programs can each display in their own windows, but prevent them from destroying graphics being displayed by other windows.
Peripheral devices are managed in different ways according to the characteristics of the device. For example, sound output from multiple processes will be combined for simultaneous output to the speakers (or other output devices). However, when a process accesses a printer, output from that processes is collected into a document, and the documents are queued for sequential printing, because simultaneous access would result in garbled output.
=== Security Enforcement ===