RAM is an abbreviation for Random Access Memory. This is a sort of computer memory, that, unlike other storage devices including hard disks or DVDs, permits the info to be accessed directly without reading the previous content located in it. Each time a program is started, it's stored in the RAM, due to the fact that it could be accessed considerably quicker than if it was read from another media device. With regards to the web hosting service itself, extra RAM means that more web apps can work concurrently on a given web server, especially if they are resource-demanding and are accessed by a large amount of people concurrently. Not like a shared web hosting solution where the resources of a given account may be flexible and sometimes depend on what other users consume too, a VPS has a guaranteed amount of RAM you can use always. That memory is allocated to one server only and won't be used by other customers even in case it's not in use.