An emulator is a program which mimics other systems, such as game consoles. Emulators try to translate or interpret the original program code of the original game and try to make it work on your PC. Games for emulators of cartridge based game consoles are usually stored in ROM files. Games for emulators of CD based game consoles like the Playstation however use the original game CD.
What Is a ROM?
Most classic games are stored on game cartridges. The games are stored on those cartridges using ROM chips (Read Only Memory). Some people have created special devices which can read the data from those ROM chips and which can save that data on a PC in a ROM file. In other words, a ROM file contains all data from a game cartridge.
