RAM, that is short for Random Access Memory, is a computer storage media that could be accessed much quicker than a disk drive, as the information can be read randomly, skipping the bytes before the needed info is reached. On a hosting server, the RAM is used to load scripts and web programs once they are executed, so the more RAM you can use, the more apps you will be able to run simultaneously and the more people shall be able to surf your sites with no effect on the site’s/server’s performance. Unlike a disk drive, however, the RAM is employed for non permanent storage purposes, since the information is lost the moment 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 could change according to what the other customers on the same web server use. Using a virtual or a dedicated server, however, you'll have a fixed amount of RAM which won't be used by anyone else even if you don't use it at a certain time.