RAM (Random Access Memory) is the working memory expressed in a number of GigaBytes (GB). RAM is used to (temporarily) store (processor) data and is very decisive for the speed of applications and websites.
How much RAM do I need?
Let’s take a look at a wonderful Cloud hosting company. Their cheapest shared web hosting plan offers 5GB of RAM which is more than enough for a single website. The most expensive shared plan has a whopping 25GB memory good for unlimited websites.
By the way, I use this Cloud Hosting Service myself on a daily basis and I love it!
Hopefully this summary was good enough to explain what is RAM.