RAM, that stands for Random Access Memory, is a computer storage media that may be accessed considerably faster than a hard disk, as the info can be read randomly, skipping the bytes before the needed data is reached. On a web server, the RAM is used to load scripts and web applications after they are executed, so the more RAM you can use, the more applications you'll be able to run simultaneously and the more people shall be able to look through your Internet sites without any effect on the site’s/server’s functionality. Different from a disk drive, however, the RAM is used for momentary storage purposes, as the information is lost once the power is shut off. If you use a shared web hosting account, the physical memory which your scripts could use may be limited and may change depending on what the other customers on the same machine use. With a virtual or a dedicated web server, alternatively, you shall have a fixed amount of RAM that will not be used by anyone else even if you don't use it at a certain time.