RAM is an abbreviation for Random Access Memory. This is a kind of computer memory, which, different from other storage devices such as hard disks or DVDs, enables the data to be accessed directly without reading the previous content saved in it. Anytime a program is launched, it's stored within the RAM, because it may be accessed much quicker than if it was read from another media. With regards to the website hosting service itself, more RAM means that more web applications can work at the same time on a certain web server, particularly if they're resource-demanding and are accessed by a large number of people simultaneously. Different from a shared web hosting package where the resources of a given account can be flexible and often depend on what other end users consume as well, a VPS has a guaranteed amount of RAM which can be used all the time. That memory is assigned to one server only and shall not be used by other customers even in case it is not in use.