At a high-level, computers work by taking information that’s frequently accessed on the hard disk and loading it into RAM so that when a running application needs it again, it can access it in RAM rather than from the hard drive itself.
The idea behind this is so that it improves performance and this is why having a lot of memory can often give you increased performance. Today, it’s not uncommon to have 16GB of RAM available in a computer, so the amount of information that can be held in RAM is pretty impressive.
Let’s say that you’re running some intense applications, or you’re working with a demanding application, and you’re exhausting the available RAM. What happens then? At this point, the computer ends up thrashing. Sounds like fun (if you’re at a hard rock concert, maybe), right? But the gist of it is that you end up taking information in RAM, writing it back to disk, and then replacing that data with new data from the disk.
Wikipedia defines it like this:
In computer science, thrashing occurs when a computer’s virtual memory subsystem is in a constant state of paging, rapidly exchanging data in memory for data on disk, to the exclusion of most application-level processing. This causes the performance of the computer to degrade or collapse greatly.
The emphasis added is my own because it’s ultimately the point I want to bring up as it relates to the rest of this post.
