OK, first off I know what RAM "is". So I don;t need an article to tell me.
RAM is "information purgatory" in the biblical sense. Data goes there to rest, but not to reside.
So, how much is enough, is dependent on your usage. If you have, my browsing habits, (open tabs, but consider them "too valuable to close"), then a 32 bit OS & its max of 4 GB of RAM, is never enough. I'm always "running at red line" with the machine I use for the web.
In today's world, an SSD is a must, not a luxury.
Personally, I've never given it too much thought. I just light up another machine, which is my idea of "multitasking"
Other than that, open task manager and find our how much RAM YOU need, don't measure against anybody else's requirements,
Ironically, the machines I need the most RAM on, are the ones that have the least.