RAM, which refers to Random Access Memory, is a computer storage media which is accessed faster than a hard disk drive, as the info can be read randomly, skipping the bytes before the needed info is reached. On a server, the RAM is employed to load scripts and web applications once they are executed, so the more RAM you may use, the more applications you will be able to run concurrently and the more people shall be able to explore your sites without any effect on the site’s/server’s general performance. Different from a disk drive, however, the RAM is used for temporary storage purposes, as the info is lost the moment 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 may change based on what the other customers on the same web server use. Using a virtual or a dedicated hosting server, alternatively, you shall have a guaranteed amount of RAM which won't be used by anybody else even if you don't use it at a certain time.