RAM, that refers to Random Access Memory, is a computer storage media that could be accessed faster than a disk drive, due to the fact that the data can be read randomly, skipping the bytes before the needed data is reached. On a hosting server, the RAM is used to load scripts and web apps when they are executed, so the more RAM you may use, the more programs you'll be able to run at the same time and the more people shall be able to surf your sites without effect on the site’s/server’s performance. In contrast to a disk drive, however, the RAM is used for temporary 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 which your scripts could use may be limited and can change depending on what the other customers on the same web server use. Using a virtual or a dedicated web server, alternatively, you shall have a guaranteed amount of RAM which won't be used by anybody else even when you do not use it at a certain time.