RAM, that refers to Random Access Memory, is a computer storage media which may be accessed considerably faster than a hard disk drive, because the data can be read randomly, skipping the bytes before the needed information is reached. On a server, the RAM is employed to load scripts and web programs when they are executed, so the more RAM you may use, the more programs you shall be able to run concurrently and the more people will be able to explore your sites without effect on the site’s/server’s functionality. Different from 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. When you use a shared web hosting account, the physical memory which your scripts may use may be limited and could change based on what the some other clients on the same web server use. With a virtual or a dedicated server, on the other hand, you'll have a guaranteed amount of RAM that will not be used by anyone else even if you don't use it at a particular time.