RAM, that is short for Random Access Memory, is a computer storage media that is accessed way quicker than a disk drive, due to the fact that the data can be read randomly, skipping the bytes before the needed information is reached. On a web server, the RAM is used to load scripts and web programs when they are executed, so the more RAM you may use, the more applications you shall be able to run concurrently and the more people shall be able to explore your websites with no effect on the site’s/server’s performance. Different from a disk drive, however, the RAM is used for temporary storage purposes, since the info is lost as soon as the power is shut off. In case you use a shared web hosting account, the physical memory your scripts can use may be limited and may change based upon what the other customers on the same server use. With a virtual or a dedicated server, however, you will have a set amount of RAM which will not be used by anybody else even if you don't use it at a given time.