RAM is an abbreviation for Random Access Memory. This is a type of computer memory, that, unlike other storage devices including harddrives or DVDs, enables the information to be accessed directly without reading the previous content located within it. Anytime a program is started, it is stored in the RAM, due to the fact that it can be accessed much faster than if it was read from another media device. With regards to the web hosting service itself, additional RAM means that more web applications can run concurrently on a certain server, particularly when they're resource-demanding and are accessed by a significant number of people concurrently. Not like a shared web hosting plan in which the resources of a certain account may be flexible and sometimes depend on what other end users consume too, a VPS provides a guaranteed amount of RAM which can be used all the time. That memory is allotted to one server only and won't be used by other customers even if it's not in use.