RAM, which refers to Random Access Memory, is a computer storage media that may be accessed faster than a disk drive, because the data can be read randomly, skipping the bytes before the needed info is reached. On a server, the RAM is used to load scripts and web applications once they are executed, so the more RAM you are able to use, the more apps you'll be able to run at the same time and the more people will be able to browse your sites without any effect on the site’s/server’s functionality. Unlike a disk drive, however, the RAM is employed for temporary storage purposes, since the information is lost the moment the power is shut off. In case you use a shared web hosting account, the physical memory that your scripts can use may be limited and might change based upon what the other customers on the same web server use. Through a virtual or a dedicated web server, however, you shall have a fixed amount of RAM which will not be used by anyone else even when you don't use it at a given time.