RAM, that stands for Random Access Memory, is a computer storage media which is accessed faster than a disk drive, simply because the info can be read randomly, skipping the bytes before the needed information is reached. On a hosting server, the RAM is employed to load scripts and web apps after they are executed, so the more RAM you may use, the more apps you'll be able to run at the same time and the more people shall be able to look through your websites without any effect on the site’s/server’s overall performance. Different from a disk drive, however, the RAM is used for temporary storage purposes, because the info is lost as soon as the power is shut off. In case you use a shared web hosting account, the physical memory your scripts could use may be limited and can change based upon what the some other clients on the same hosting server use. With a virtual or a dedicated hosting server, alternatively, you shall have a fixed amount of RAM that will not be used by anyone else even when you do not use it at a particular time.