RAM is an abbreviation for Random Access Memory. This is a kind of computer memory, which, in contrast to other storage devices like harddrives or DVDs, allows the info to be accessed directly without reading the previous content stored in it. Whenever an application is started, it's stored in the RAM, due to the fact that it can be accessed much more quickly than if it was read from another media device. With regards to the hosting service itself, additional RAM means that more web applications can run all at once on a given server, especially when they're resource-demanding and are accessed by a significant number of people simultaneously. Different from a shared web hosting plan in which the resources of a certain account can be flexible and often depend on what other users consume as well, a VPS offers a guaranteed amount of RAM which can be used at all times. That memory is assigned to one web server only and won't be used by other clients even when it is not in use.