RAM is an abbreviation for Random Access Memory. This is a sort of computer memory, that, different from other storage devices including hard disk drives or DVDs, enables the info to be accessed directly without reading the previous content located inside it. Whenever an application is launched, it is stored within the RAM, as it could be accessed much more quickly than if it was read from another media. In terms of the web hosting service itself, more RAM means that more web apps can run all at once on a certain web server, particularly when they're resource-demanding and are accessed by a large number of people simultaneously. Not like a shared web hosting solution where the resources of a certain account can be flexible and sometimes depend on what other users consume also, a VPS features a guaranteed amount of RAM which can be used at all times. That memory is assigned to one server only and will not be used by other clients even in case it's not used.