RAM is an abbreviation for Random Access Memory. This is a sort of computer memory, that, unlike other storage devices including harddrives or DVDs, allows the info to be accessed directly without reading the previous content stored inside it. Whenever an app is started, it is stored in the RAM, since it could be accessed considerably faster than if it was read from another media device. With regards to the web hosting service itself, extra RAM means that more web applications can operate at the same time on a certain server, especially if they are resource-demanding and are accessed by a great number of of people simultaneously. Not like a shared web hosting package in which the system resources of a given account may be flexible and sometimes depend on what other end users consume too, a VPS features a guaranteed amount of RAM that can be used always. That memory is allocated to one web server only and shall not be used by other clients even when it's not in use.