RAM, which is short for Random Access Memory, is a computer storage media that is accessed much more quickly than a hard disk drive, as the info can be read randomly, skipping the bytes before the needed info is reached. On a web server, the RAM is used to load scripts and web programs when they are executed, so the more RAM you can use, the more programs you will be able to run concurrently and the more people will be able to explore your websites without effect on the site’s/server’s performance. Unlike a disk drive, however, the RAM is used for short-term storage purposes, as the info is lost the moment the power is shut off. When you use a shared web hosting account, the physical memory that your scripts are able to use may be limited and may change depending on what the some other clients on the same machine use. With a virtual or a dedicated hosting server, on the other hand, you shall have a fixed amount of RAM which won't be used by others even when you don't use it at a given time.