RAM is an abbreviation for Random Access Memory. This is a type of computer memory, which, unlike other storage devices such as harddrives or DVDs, permits the data to be accessed directly without reading the previous content located in it. Whenever an app is started, it's stored inside the RAM, due to the fact that it may be accessed much quicker than if it was read from another media device. With regard to the hosting service itself, extra RAM means that more web applications can run all at once on a certain server, especially when they're resource-demanding and are accessed by a large number of people at the same time. Not like a shared web hosting plan in which the resources of a particular account could be flexible and quite often depend on what other users consume also, a VPS features a guaranteed amount of RAM you can use all the time. That memory is assigned to one hosting server only and shall not be used by other customers even in case it's not being used.