RAM, that is short for Random Access Memory, is a computer storage media that could be accessed much more quickly than a hard drive, because the data can be read randomly, skipping the bytes before the needed information is reached. On a server, the RAM is employed to load scripts and web apps after they are executed, so the more RAM you are able to use, the more apps you'll be able to run simultaneously and the more people shall be able to explore your websites without any effect on the site’s/server’s overall performance. Unlike a disk drive, however, the RAM is used for short-term storage purposes, because the info is lost once 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 on what the some other clients on the same machine use. Using a virtual or a dedicated server, alternatively, you will have a fixed amount of RAM which won't be used by anyone else even if you don't use it at a given time.