RAM, which stands for Random Access Memory, is a computer storage media which can be accessed much faster than a hard disk, due to the fact that the information 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 apps once 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 look through your sites with no effect on the site’s/server’s overall performance. In contrast to a disk drive, however, the RAM is used for temporary storage purposes, due to the fact that the info is lost when the power is shut off. In case you use a shared web hosting account, the physical memory that your scripts are able to 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, however, you will have a set amount of RAM that will not be used by others even when you don't use it at a certain time.