Random Access Memory
From Unofficial BOINC Wiki
 Random-access memory
RAM stands for "random access memory." Although, technically speaking, this refers to the fact that the contents of the memory are randomly accessible (see below), when most people talk about RAM, they are in fact talking about a computer's main memory, the main characteristics of which are--in addition to the fact of random accessibility--that:
- power is required to retain the contents (that is, if you shut down the computer, everything in RAM is lost) and
- the contents can be modified easily.
RAM contains both instructions (software, typically loaded from hard disk) and data.
 What is random access?
The term "random access" refers to a property of the memory device by which the time to access any item of information is a constant, no matter where it is physically stored within the device. In other words, the time it takes to get item "A" is no different than the time it takes to get item "B" (as opposed to sequential access, which is similar to a cassette tape, in that you have to fast-forward through "A" to get to "B," or rewind through "B" to get to "A.")
In most modern computers the main memory system does have a consistent and predictable access time (though this is slowly changing as the Non-Uniform Memory Access memory systems begin to make a larger inroad on systems). In most PCs, the only places where the variability in access time is measurable are the CD and disk drives. These components have a non-uniform access time to a particular item of data.