RAM, that stands for Random Access Memory, is a computer storage media that is accessed faster than a hard disk drive, simply because the info can be read randomly, skipping the bytes before the needed information is reached. On a server, the RAM is used to load scripts and web applications after they are executed, so the more RAM you may use, the more programs you shall be able to run concurrently and the more people shall be able to look through your sites without effect on the site’s/server’s general performance. Different from a disk drive, however, the RAM is employed for non permanent storage purposes, as the info is lost the moment the power is shut off. If you use a shared web hosting account, the physical memory which your scripts are able to use may be limited and can change based upon what the other customers on the same hosting server use. With a virtual or a dedicated server, alternatively, you will have a guaranteed amount of RAM which won't be used by anybody else even when you don't use it at a given time.