In order to understand how a computer uses memory, it's important to first understand the two different types of memory that a computer uses and how. RAM, or random access memory, is the available space a computer has to operate any of its normal processes and specific applications. It's analogous to a human's metabolism. ROM, or read only memory, is where a computer stores all of its files and other information for recall at a later time by the user.

Both RAM and ROM memory are measured by the amount of information it can store. These days, this is usually measured in gigabytes. An average retail computer will usually have a gigabyte or two in RAM and can have up to 120 or more gigabytes in ROM.

Generally having more memory make a computer more valuable, but a computer uses the memory in different ways. When it comes to RAM, the more a computer has, the faster it is able to run, and the more applications it can manage simultaneously. RAM, similar to a microprocessor, is made up of millions of transistors and capacitors. One transistor/capacitor pair makes up one cell. Each cell is capable of remembering one bit of data. If the PC has a one gigabyte RAM memory chip, it has the capacity of remembering 8,589,934,592 individual binary numbers, or fractions of information. RAM memory is in a state of constant renewal, remembering information and deleting the information as it is no longer needed.

ROM, on the other hand, pertains to information storage only. ROM is comprised of the same transistors/capacitor pairs, only the memory is static. Information saved in ROM, will remain in ROM until the user requests it to be overwritten. Information is never truly erased from a PC's ROM memory, only the directories that point the PC to stored information is. This makes it virtually impossible to permanently erase information that has been saved on a PC, unless taken to a professional.

Both RAM and ROM can be expanded on an existing PC, making it possible to utilize an older model for longer before replacing. PC memory can be purchased at almost any home electronics store, like BestBuy, RadioShack and even Wal-Mart. ROM must be upgraded by a professional, either in a repair center or retail outlet.

It is also possible to free up memory, by regularly maintenance your PC. You should defragment and delete your temporary Internet file cache in order to free up memory that would otherwise be wasted. Not only do these actions free up memory, but they also improve the performance of your PC.

So, when deciding what PC to purchase the next time you need a new PC, take time to evaluate a PC's available memory. It can make the difference between getting the computer you need and having to replace or upgrade the memory in six months.