RAM, which is short for Random Access Memory, is a computer storage media which can be accessed much faster than a hard disk, as the information 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 apps when they are executed, so the more RAM you are able to use, the more applications you'll be able to run all at once and the more people will be able to check out your sites without any effect on the site’s/server’s performance. Different from a disk drive, however, the RAM is employed for momentary storage purposes, since the information is lost once the power is shut off. In case you use a shared web hosting account, the physical memory which your scripts can use may be limited and can change depending on what the other customers on the same web server use. Using a virtual or a dedicated server, alternatively, you shall have a fixed amount of RAM which will not be used by others even when you do not use it at a given time.