RAM is an abbreviation for Random Access Memory. This is a sort of computer memory, that, different from other storage devices including hard disk drives or DVDs, allows the information to be accessed directly without reading the previous content stored within it. Whenever a program is launched, it is stored inside the RAM, as it can be accessed much more quickly than if it was read from another media. With regards to the hosting service itself, extra RAM means that more web applications can run at the same time on a certain server, especially when they're resource-demanding and are accessed by a large number of people all at once. Different from a shared web hosting solution where the system resources of a particular account can be flexible and often depend on what other end users consume as well, a VPS features a guaranteed amount of RAM that can be used always. That memory is allotted to one web server only and won't be used by other customers even if it's not in use.