An emulator is a computer program or hardware that makes one kind of computer behave like a different one, so that it can use the same programs or do the same things as the other one. They are best for using old software and games on newer computers. They can be hardware that you add to the computer, or software that you use on it. Some types of emulators require newer computers that have the right system requirements. For example, you need a processor that is fast enough to meet the demands of the emulator. Memory (both RAM and hard drive space) may be another factor to help it run smoothly and more accurately. With the more advanced emulators, if your computer is too old, the emulator or even the operating system may crash.