RAM, which means Random Access Memory, is a computer storage media that can be accessed considerably faster than a hard disk drive, simply because the information can be read randomly, skipping the bytes before the needed info is reached. On a hosting server, the RAM is employed to load scripts and web programs when they are executed, so the more RAM you may use, the more applications you will be able to run all at once and the more people will be able to surf your websites with no effect on the site’s/server’s overall performance. Different from a disk drive, however, the RAM is used for non permanent storage purposes, as the info is lost when the power is shut off. In case you use a shared web hosting account, the physical memory which your scripts may use may be limited and might change depending on what the other customers on the same hosting server use. With a virtual or a dedicated server, on the other hand, you'll have a guaranteed amount of RAM which won't be used by anybody else even when you do not use it at a certain time.