RAM is an acronym for Random Access Memory. It is a type of computer memory akin to a person's short-term memory. Data that must be accessed quickly is kept in RAM, such as running applications and open files. When a computer does not have enough RAM, it is forced to allocate part of the hard disk in place of the missing RAM, which hurts performance. Modern operating systems such as OS-X, Windows XP, or Linux need about 256 MB of RAM to perform satisfactorily, and 'heavy' operating systems such as Windows Vista require 1 GB (1025 MB) of RAM to run. Users who open many files or programs at once, or those who play graphics intensive games or video, may need twice that amount or RAM. To better understand RAM, think of a person with a notepad. We'll call him Bill, and if you tell him a 7 digit phone number, he will be able to remember it for a day without writing it down. Additionally, he will be able to dial the number quickly. Bill's memory is like RAM: it holds a limited amount of information for a limited time, but it is accessed quickly. If phone numbers were 96 digits long Bill would not be able to remember it, he would need to write the phone number down in his notepad. Although the information (phone number) would never be erased (forgotten), it would take Bill longer to pull out his notepad, look up the phone number, and then to dial it than it would take him to dial the number from memory. Bill's notepad is akin to what is called 'swap space': an area of the hard disk that is used in place of RAM when the computer does not have enough RAM. RAM logo Although there are several types of RAM on the market today, they are not interchangeable. That means that before purchasing new RAM, the user must check what type of RAM is currently in his system, and what types of RAM his motherboard will accept. Also, extreme care must be taken when handling RAM modules. Often, just touching them in the wrong place will partially damage them. This is a common cause of frustration, as damaged RAM will continue to function, but only part of the RAM will be available. For instance, a 128 MB RAM module that has been in a pants pocket may have 32 MB damaged, and it will provide only 96 MB of usable RAM to the computer. The damage is not visible to the eye, and only with specialized software or equipment can the damage be assessed.