What Is an Emulator?

The tech that lets computers copy each other

An emulator is a computer or program that emulates, or imitates, another computer or program. For example, emulators make it possible to run Windows on a Mac computer and vice versa. Learn about how emulators work and why someone might use them.

A smartphone OS running on a computer monitor.

What Is an Emulator?

The concept of computer emulation was conceived by IBM as a way to run programs designed for their older devices on newer models. The method they used relied on a combination of software and hardware dedicated to emulation. Rather than designing brand new applications for their new computers, built-in backwards compatibility gave developers greater flexibility.

Today, the term emulator is commonly used in the context of video games. Video game emulators became popular during the 1990s because they allowed people to play older console games on modern desktop computers. With the proliferation of smartphones and tablets, emulators capable of running iOS or Android on PCs are also in increasingly high demand.

How Emulators Work

Different types of emulators employ various emulation techniques, but the end goal is the always same: to replicate the experience of using the original hardware or software. Some emulators even exceed the performance of the original product and include additional features.

Emulation requires a lot of computational resources. Due to this "emulation tax," many lag behind their real-world counterparts in terms of performance. Since they’re usually created by unpaid programmers, emulators can take a long time to develop.

Emulation is closely related to the concept of virtualization. Virtual machines are a type of emulator that can run on the underlying hardware of the host system. Therefore, there’s no emulation tax, but virtual machines are limited in what they can do compared to the original machine.

Why Use Emulators?

Software tends to be platform-specific, which is why developers make separate applications for Android, iOS, Windows, and Mac. If you're a Mac user and you want to use an app that's only available for Windows, your only option (besides buying a Windows computer) is to use an emulator.

Emulators also play an import role in digital preservation. Programs stored on obsolete formats, such as old game cartridges, can be downloaded as ROM (read-only memory) files using a special device. The ROMs can then be played using an emulator for the original game system they were designed for.

Examples of Emulators

There are countless commercial and open-source emulators available for every major operating system. Here are some examples: