RAM is an abbreviation for Random Access Memory. This is a kind 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 stored inside it. Every time an app is launched, it is stored within the RAM, as it could be accessed much quicker than if it was read from another media. With regard to the website hosting service itself, additional RAM means that more web applications can work at the same time on a given web server, especially when they are resource-demanding and are accessed by a great number of of people concurrently. Not like a shared web hosting package in which the system resources of a certain account could be flexible and frequently depend on what other end users consume too, a VPS features a guaranteed amount of RAM which you can use at all times. That memory is allocated to one web server only and won't be used by other clients even if it is not being used.