Persistent storage is essential to every system that we can think of, and we can hardly think of a computer without it. However, managing disks is not as simple as it might appear on a surface level.

Concurrency is a powerful tool to increase performance in applications. This is usually accomplished using threads.

Sometimes we don't have a lot of memory to access. In those cases, we need a place to put our data. The natural solution is to put data in the disk, which has very high storage. This is known as swapping.

The main problem that segments have introduced to managing memory space is that their variable size wastes memory through fragmentation. Fixed-size pieces that are easier to handle are much more popular: these are known as pages.

Accessing physical memory can cause big issues if we do it directly. How can we virtualize the memory like the CPU so we can use it efficiently and safely?

The way that the operating system decides which processes to run and when is a complicated process known as scheduling. This is how it works.

We need a way to map on to the physical CPU through our operating system. We do this through virtualization.