This is an excellent question when buying a new computer, and it is also very important to consider how much mass storage will be required as well. Most mid-range computers are equipped with 1-2 gigabytes of RAM, or Random Access Memory. RAM is extraordinarily important to the proper function of a computer, since the amount of available RAM affects the entire operation of every single program in a computer, from the operating system to the word processor to the web browser. It even affects how well computers can function with external devices such as digital cameras and printers.

In order for any program to "run" or function on a computer, it must be loaded into RAM first. In much older systems, "loading" a program was often a very slow process, requiring a machine to read the entire application off a mass storage device such as a floppy disk while copying it into much faster RAM so the processor could access the different instructions quickly enough for the program to operate.

(There are those who might argue that the current process of "loading" programs into computer memory is still a very slow process, but that is another article.)

This same process takes place each time a user launches their browser or word processor. The computer "loads" or copies the application instructions into RAM, where the processor can read and understand the program quickly enough for it to be useful.

If the computer runs out of space, or doesn't have enough RAM to load all of the programs and their data, a process called "paging" takes place, where rarely used data or programs are removed from RAM and written back out to the mass storage device to make room for other more important or recently activated applications. When a computer's RAM is overloaded, programs slow to a crawl, even affecting the speed of the visual display while the disk operates continuously, writing and copying RAM data out to disk.

It is not uncommon for programs such as browsers and word processors to consume hundreds of megabytes of RAM, considerable percentages of even a newer computer's memory, by themselves, leaving very little room for other programs, such as the operating system, games or e-mail programs, to function.

Essentially, the more RAM a computer has, the more can be done simultaneously with it. If every program launched has ample memory, the entire operation of the machine should proceed at full speed with no performance problems. Of course, there are limits to the amount of RAM that can be installed on current machines, but there are custom-built computers with as much as eight gigabytes of RAM, around four times the average amount installed on a commercially available pre-built computer. For maximum performance, a PC should be equipped with as much RAM as possible.

Generally speaking, the cost-to-performance ratio of RAM compared to say, a processor or CPU, is much lower, making an increase in RAM capacity one of the least expensive ways to improve the performance of nearly any computer.