Conclusion
Memory hierarchy: virtual memory

Virtual memory is the part of the memory hierarchy between main memory and secondary memories. Like the cache hierarchy, it acts as an adapter to take account of differences in characteristics (throughput, latency) between volatile main memory and non-volatile secondary memories, automatically managing transfers between these memories necessitated by page faults. At the same time, it gives the user the illusion of having a very large memory (hence the term "virtual memory"), as if he were the only user of the machine.

The implementation of virtual memory provides the operating system with the mechanisms to perform both functions: on the one hand, to manage automatic transfers between successive levels of the hierarchy and, on the other, to provide protection mechanisms for reading, writing or executing the various pages making up virtual memory.

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