RAM is an abbreviation for Random Access Memory. This is a sort of computer memory, which, different from other storage devices including harddrives or DVDs, enables the information to be accessed directly without reading the previous content located within it. Each time an app is launched, it is stored inside the RAM, because it may be accessed much more quickly than if it was read from another media device. With regards to the hosting service itself, extra RAM means that more web applications can work at the same time on a certain hosting server, particularly if they're resource-demanding and are accessed by a large amount of people all at once. Unlike a shared web hosting plan in which the resources of a certain account may be flexible and quite often depend on what other end users consume as well, a VPS has a guaranteed amount of RAM which can be used always. That memory is allotted to one hosting server only and shall not be used by other clients even in case it is not used.