RAM, which means Random Access Memory, is a computer storage media that could be accessed much faster than a hard disk drive, as the information can be read randomly, skipping the bytes before the needed info is reached. On a server, the RAM is employed to load scripts and web apps once they are executed, so the more RAM you can use, the more apps you will be able to run concurrently and the more people will be able to surf your websites without effect on the site’s/server’s performance. In contrast to a disk drive, however, the RAM is used for temporary storage purposes, since the information is lost as soon as the power is shut off. If you use a shared web hosting account, the physical memory your scripts may use may be limited and may change depending on what the some other clients on the same server use. With a virtual or a dedicated server, however, you will have a guaranteed amount of RAM that will not be used by anyone else even if you don't use it at a given time.