Hello Kathi
RAM (Random Access Memory) is sometimes called system memory. It is not the memory you use but rather the memory the operating system and applications use. In order to run properly your computer must have RAM to use while the system is on. Your operating system will need a certain amount of system memory to run efficiently.
A common misconception used to get people to purchase unneeded RAM upgrades is that having more RAM will make your system run faster. In fact, that is often not the case. Every operating system has a peak RAM value that will result in best performance and if you already have that amount, getting more will not provide much benefit.
There are several different types of RAM currently in computers today, and RAM technology changes often. If you are thinking about upgrading your memory it will be important to talk to someone about what type of RAM you are currently using. If the wrong type is purchased then adding more will actually cause the older sticks of RAM to run slower.
High performance computers will benefit from good quality RAM because it is a cornerstone to a computer system. Since the processor uses the RAM often, changes to the RAM will indirectly affect your experience. There are a number of things which affect the quality of your RAM. Front Bus Speed, type of architecture, and timings can all affect performance. Most computer manufacturers count on you not knowing much about these topics and will cut corners by offering lower speed memory without you knowing what you are getting.