An emulator is a software or hardware tool that allows one computer system to mimic the functions of another. This enables users to run applications or games designed for a different platform, such as a video game console or an older operating system. Emulators are commonly used for testing software, playing retro games, or running applications that are not available on a user's current device. Emulators work by replicating the original system's architecture, including its CPU, memory, and input/output processes. This allows the emulated software to operate as if it were running on its native hardware. Popular examples of emulators include those for Nintendo and Sega consoles, which let users enjoy classic games on modern computers.