RAM is an abbreviation for Random Access Memory. This is a type of computer memory, which, different from other storage devices such as hard disks or DVDs, permits the information to be accessed directly without reading the previous content saved inside it. Whenever an app is launched, it's stored in the RAM, as it can be accessed considerably faster than if it was read from another media device. With regard to the hosting service itself, more RAM means that more web apps can operate concurrently on a certain server, particularly when they are resource-demanding and are accessed by a large amount of people concurrently. Unlike a shared web hosting plan where the system resources of a given account can be flexible and quite often depend on what other users consume as well, a VPS features a guaranteed amount of RAM which can be used all the time. That memory is allocated to one hosting server only and will not be used by other customers even when it's not used.