RAM, which refers to Random Access Memory, is a computer storage media which may be accessed noticeably faster than a disk drive, as 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 after they are executed, so the more RAM you are able to use, the more programs you will be able to run simultaneously and the more people shall be able to browse your websites without effect on the site’s/server’s general performance. Different from a disk drive, however, the RAM is employed for short-term storage purposes, as 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 are able to use may be limited and can change depending on what the other customers on the same hosting server use. Using a virtual or a dedicated server, alternatively, you shall have a guaranteed amount of RAM which will not be used by anybody else even if you don't use it at a certain time.