RAM, that refers to Random Access Memory, is a computer storage media which may be accessed much more quickly 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 employed to load scripts and web programs once they are executed, so the more RAM you are able to use, the more applications you'll be able to run concurrently and the more people will be able to check out your sites without effect on the site’s/server’s functionality. In contrast to a disk drive, however, the RAM is used for short-term storage purposes, because the data is lost the moment the power is shut off. When you use a shared web hosting account, the physical memory which your scripts could use may be limited and could change based on what the other customers on the same web server use. Through a virtual or a dedicated server, alternatively, you shall have a fixed amount of RAM that will not be used by others even if you don't use it at a certain time.