RAM, that means Random Access Memory, is a computer storage media that may be accessed considerably faster than a disk drive, as the information can be read randomly, skipping the bytes before the needed data is reached. On a web server, the RAM is used to load scripts and web applications after they are executed, so the more RAM you may use, the more applications you'll be able to run concurrently and the more people shall be able to check out your sites with no effect on the site’s/server’s general performance. Unlike a disk drive, however, the RAM is used for non permanent storage purposes, because the info is lost as soon as the power is shut off. If you use a shared web hosting account, the physical memory your scripts may use may be limited and could change based upon what the other customers on the same web server use. Through a virtual or a dedicated hosting server, alternatively, you will have a set amount of RAM that won't be used by anybody else even if you don't use it at a given time.