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, allows the info to be accessed directly without reading the previous content stored within it. Whenever an application is started, it's stored inside the RAM, as it may be accessed much more quickly than if it was read from another media device. With regard to the hosting service itself, extra RAM means that more web apps can run all at once on a given server, especially when they're resource-demanding and are accessed by a large number of people concurrently. Not like a shared web hosting plan in which the resources of a certain account could be flexible and frequently depend on what other users consume also, a VPS provides a guaranteed amount of RAM that can be used at all times. That memory is allocated to one hosting server only and shall not be used by other clients even when it is not in use.