RAM is an abbreviation for Random Access Memory. This is a sort of computer memory, that, unlike other storage devices including hard disks or DVDs, permits the data to be accessed directly without reading the previous content located inside it. Each time an app is started, it's stored in the RAM, because it can be accessed much faster than if it was read from another media device. In terms of the website hosting service itself, additional RAM means that more web apps can operate concurrently on a certain server, particularly if they are resource-demanding and are accessed by a large number of people at the same time. Unlike a shared web hosting package where the resources of a certain account can be flexible and frequently depend on what other end users consume also, a VPS has a guaranteed amount of RAM that can be used at all times. That memory is allocated to one hosting server only and won't be used by other clients even in case it's not in use.