RAM is an abbreviation for Random Access Memory. This is a sort of computer memory, which, different from other storage devices such as hard disks or DVDs, allows the data to be accessed directly without reading the previous content stored inside it. Anytime a program is launched, it's stored in the RAM, because it could be accessed considerably quicker than if it was read from another media. With regards to the website hosting service itself, extra RAM means that more web applications can run all at once on a given web server, especially if they are resource-demanding and are accessed by a significant number of people all at once. In contrast to a shared web hosting plan in which the system resources of a given account may be flexible and sometimes depend on what other users consume also, a VPS provides a guaranteed amount of RAM that can be used always. That memory is allotted to one server only and will not be used by other customers even when it's not in use.